[M] Change in coreboot[master]: soc/amd/common/block/apob: Add hashed APOB support

[Fred Reitberger (Code Review)]

Attention is currently required from: Jason Glenesk, Raul Rangel, Matt DeVillier, Martin Roth, Felix Held.

Fred Reitberger has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/67301 )

Change subject: soc/amd/common/block/apob: Add hashed APOB support
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Patch Set 3:

(1 comment)

File src/soc/amd/common/block/apob/apob_cache.c:

https://review.coreboot.org/c/coreboot/+/67301/comment/3afe3057_f0228c17 
PS2, Line 22: RW_MRC_HASH
> SPI is random access, so you can call `rdev_readat` with what ever offset you want. […]

Okay, I'll give that a test and see if I can simplify this even more.

I don't have older hardware, so I have no way to test cezanne/zork, but they should be able to support this as long as there are 8 bytes free at the end of the MRC_CACHE block.  My plan was to enable it first on chausie/skyrim and then opt-in other boards from there.