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