[S] Change in coreboot[main]: cpu/x86/smm: Fix get_save_state calculation

[Jérémy Compostella (Code Review)]

Attention is currently required from: EliasOfWaffle, Eugene Myers, Martin L Roth, Matt DeVillier, Michał Żygowski, Paul Menzel, Stefan Reinauer.

Jérémy Compostella has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/78889?usp=email )

Change subject: cpu/x86/smm: Fix get_save_state calculation
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Patch Set 4: -Code-Review

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/78889/comment/e3828b24_52706035 :
PS4, Line 9: When the SMI transfer monitor (STM) is configured, get_save_state returns an incorrect pointer to the cpu save state because the size (rounded up to 0x100)of the processor System Management Mode (SMM) descriptor needs to be subtracted out in this case.
missing space after the parenthesis.

File src/cpu/x86/smm/smm_module_handler.c:

https://review.coreboot.org/c/coreboot/+/78889/comment/b76e82f9_19342259 :
PS4, Line 110: 		stm_psd_size = ALIGN_UP(sizeof(TXT_PROCESSOR_SMM_DESCRIPTOR),
`ALIGN_UP(sizeof(TXT_PROCESSOR_SMM_DESCRIPTOR), 0x100)` is also used in `src/cpu/x86/mp_init.c::fill_mp_state_smm()`. Isn't time to define a macro, a shared function or whatever in order to prevent an inconsistency ?