[M] Change in coreboot[master]: post_codes: Add an optional "Prefix" to post codes sent to IO

[Felix Held (Code Review)]

Attention is currently required from: Jason Glenesk, Raul Rangel, Martin L Roth, Matt DeVillier, Martin Roth, Fred Reitberger.

Felix Held has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/71712 )

Change subject: post_codes: Add an optional "Prefix" to post codes sent to IO
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Patch Set 1:

(1 comment)

Patchset:

PS1: 
wouldn't be adding 4 bit post code support to coreboot and then adding a coreboot-specific prefix in the upper byte be a better solution? sure, that will only work with 4 byte post code support, but at least on current AMD platforms that's the standard