This last minute pull-request is intended to fix some drivers
when used on ARC boards. The problem was introduced by
https://gitlab.denx.de/u-boot/u-boot/-/commit/07906b3dad157bd58411664bcc6a2a7976d5e0a9

What happened while doing one pretty simple improvement to make
U-Boot port more flexible and portable (by switching accessors from
assembly-written to plain C version) we implicitly added 2 problems:

 1. Downgraded accessors from being volatile which signalled to
    the compiler that it's now possible to do all kinds of optimizations
    which may easily include merge of subsequent byte reads/writes into
    word operations. Which is OK for accessing mormal memory but
    breaks operation of peripherals if we access its memory-mapped regs
    in such a "creative" manner.
 2. As a part of assembly-written implementation we had compiler barriers
    in form of the following construction 'asm volatile("" : : : "memory")',
    and we dropped it in C implemntation. This in its turn enabled compiler
    to mess with instruction ordering. Guess what it gives us in the end :)

So with all that we had in some corner-cases veeery funny instruction flows
generated. And in particular it broke DW SPI functionality when we were
writing large amount of data. Funny enough our tests which were writing
small amount of data still worked and only by the chance we caught that
breakage and unrolled that quite interesting loop of unexpected
problems.

The road to hell is paved with good intentions. Amen :)

This is last minute change which fixes problems in runtime on
AXS10x board caused by some changes in NAND framework and
tiny documentation improvement.

Anyways NAND flash storage was never really used on the board for various
reasons and now we decided to drop it for good.

Note this change only touches 1 ARC board so that should be safe for others.
As usual - build tested in TravisCI, see
https://travis-ci.org/abrodkin/u-boot/builds/512041342

Here we introduce new development platfrom for ARC: HSDK 4xD.
That's pretty much the same base-board as in HSDK but with
very recent quad-core ARC HS47D in the ASIC.

Thus we try to re-use existing code as much as possible while
inevitably add some pieces needed for the new ASIC.

Also we drop selection of bounce buffers on AXS10x
as there's no use of them any longer.

More fixes and improvements for ARC here:

Fixes:
 * Take care of global uninitialized variables
   They used to be put right after .bss section and were never
   zeroed as they should be. Now merged with normal .bss

Improvements:
 * Print more verbose CPU info for boards built on real silicon
 * Add support for SD-card detection on all ARC boards
 * Quite a few fixes for IoT DK
   - Support reset by command
   - Print of CPU freq on boot
   - Link for eFlash etc

More fixes and improvements for ARC here:

Fixes (this time included for real):
 * Take care of global uninitialized variables
   They used to be put right after .bss section and were never
   zeroed as they should be. Now merged with normal .bss

Improvements:
 * Print more verbose CPU info for boards built on real silicon
 * Add support for SD-card detection on all ARC boards
 * Quite a few fixes for IoT DK
   - Support reset by command
   - Print of CPU freq on boot
   - Link for eFlash etc

Add support for DEBUG_UART on ARC devboards

This required us to do 2 things:
 1) Insert a call to debug_uart_init() in early boot code
 2) Convert serial_arc to Kconfig

Once both items above are done we just patched defconfigs.

Here we do a couple of minor fixes like:
 - Move .ivt section to the very beginning of the image
   by default which allows us to use that image put right
   at reset vector (usually 0x0)

 - Improve relocation fix-up which became required once
   we moved .ivt and understood a problem with existing implementation
   where we relied on a particular placement of sections.
   Now we don't care about placement because we just explicitly
   check for .text and in case of ARCompact .ivt sections

 - Re-implemnt do_reset() such that it calls reset_cpu() which
   could implmented for a particular board

And hte most important part we introduce support for yet another
devboard from Synopsys - EMDK.

Here we just add a tool for HSDK flashable images preparation
together with extensive documentation for HSDK board.

This will help real-life users to update U-Boot on the board.

Here we only add readme file for EMDK board
support of which was added in this release cycle.

Minor changes for ARC

1. Fix CPU clock value in HSDK's .dts so time is counted properly.
2. Enable bootelf command on EMDK

That's a set of prety minor changes and fixes for ARC.

Among them:
 * Improvement in CREG GPIO driver used on ARC dev boards
   that allow us to re-use the driver for SPI's chip select

 * Enable SPI-flsh on AXS10x boards which allows to update
   U-Boot binary that gets loaded by boot-ROM

 * Fix accommodating always utilized unaligned access by
   GCC for ARC starting from 8.1.0

Here we do a couple of impovements for all ARC boards
as well as introduce yet another developemnt board.

1. Now for ARC boards we print CPU and board info
   which is useful for users and helps with
   analysis of logs "post-mortem".

2. Synopsys IoT development kit support is added
   This one might bw a bit too late as we're past RC1
   but:
    1) This doesn't affect any other arches etc
       as we change purely ARC code.
    2) I've got a chance to talk about U-Boot on
       IoT platforms during ELCE (my proposal was on
       a wait list and only this week I've got
       an update and invitation to talk) so it would
       be good to have this board as a primer in upstream
       code-base by the time of ELCE 2018.
    3) For complete support of IoT devkit I'm yet to
       significantly rework regmap subsystem in U-Boot
       but that's a different topic and hopefully it will
       be done sometime soon... though not this release
       cycle for sure.

We introduce much better automatic identification of ARC cores.

 1. Try to match found HW features to known ARC core templates
 2. Print CPU frequency for all ARC boards
 3. Add more board-specific info

U-Boot 1.3.0 Release

U-Boot 1.3.0-rc1

U-Boot 1.3.0-rc2

U-Boot 1.3.0-rc3

U-Boot 1.3.0-rc4

U-Boot 1.3.1 Release

U-Boot 1.3.1-rc1 release