[L] Change in flashrom[main]: rpmc: add rpmc commands feature

[Matti Finder (Code Review)]

Attention is currently required from: Anastasia Klimchuk, Peter Marheine.

Matti Finder has posted comments on this change by Matti Finder. ( https://review.coreboot.org/c/flashrom/+/84934?usp=email )

Change subject: rpmc: add rpmc commands feature
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Patch Set 2:

(3 comments)

File include/rpmc.h:

https://review.coreboot.org/c/flashrom/+/84934/comment/d7912236_6d9d1418?usp... :
PS1, Line 37: 	uint8_t status;
> It looks like you use status values in the CLI and 0x80 always indicates success, but that's not a v […]
> Within JESD260 there is a specific 8-bit extended status register defined.
> The status for last command success is 0b10000000, hence the 0x80. 
> The status 0 is only used as the state immideatly after reboot, so it should never happen after one of our transmissions.
> So we could also use it as a return value without losing valuable data.
> What would you prefer keeping it close to JESD260 and returning the status register value, and documenting it better (maybe adding a enum for the values). Or cheating a bit and returning 0 on success instead of 0x80. I currently prefer the second option, with some additional defines for the bits.

File meson.build:

https://review.coreboot.org/c/flashrom/+/84934/comment/aa3c01a9_54dc9fd4?usp... :
PS1, Line 177: enabled
> `enabled` is only true if the feature is set to `enabled` (not `auto`). […]
> Done

File rpmc.c:

https://review.coreboot.org/c/flashrom/+/84934/comment/794bd7c8_11441024?usp... :
PS1, Line 287: 	unsigned char msg[RPMC_UPDATE_HMAC_KEY_MSG_LENGTH];
> I'd prefer to use initializers for arrays like this (throughout this file), to make it less prone to […]
> Done