[coreboot] SB600 SPI driver for flashrom and sst25vf040

[Wang, Qingpei]

Hi, Sean

Have you finished the patch about SB600 SPI driver? I found that
the patch you posted can not be compiled, and I had made another two
patches, one is for SB600 SPI and the other one is for sst25vf040. If
you have any latest work, please tell me, maybe we can merge our patches
into one.

Thanks

Jason Wang

BeiJing Technology Development Center

Advanced Micro Devices (AMD)