Add support for the AMD/ATI SB600 southbridge SPI functionality

This has been tested by Uwe Hermann on an RS690/SB600 board.

Corresponding to flashrom svn r351 and coreboot v2 svn r3779.

Signed-off-by: Jason Wang <Qingpei.Wang@amd.com>
Reviewed-by: Joe Bao <zheng.bao@amd.com>
Acked-by: Uwe Hermann <uwe@hermann-uwe.de>
7 files changed