arm: sunxi: Add Sunchip CX-A99 initial support

The Sunchip CX-A99 is a board used in some media players. It features:

An Allwinner A80 ARM SoC (4 * Cortex-A7 + 4 * Cortex-A15 cores)
2 GiB or 4 GiB DDR3 DRAM
AXP808 PMIC
16 GB or 32 GB eMMC
SDIO Wifi/Bluetooth/FM module
SD card slot
1 USB 3.0 connector
2 USB 2.0 connectors
SATA connector
UART connector (internally) for serial console
Ethernet connector (10/100/1000 Mbit/s)
HDMI connector
Composite video and analog audio connector
S/PDIF connector
IR remote control receiver

This patch adds a defconfig for the board. The DRAM settings are as found
in the vendor sys_config.fex file.

It has a preliminary device tree for use until a device tree is accepted
upstream, after which it can be replaced by the upstream version.

Signed-off-by: Rask Ingemann Lambertsen <rask@formelder.dk>
[squash commits, and edited new meanful commit message]
Signed-off-by: Jagan Teki <jagan@openedev.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>