[M] Change in coreboot[master]: soc/amd/mendocino: Add new 'STT_ALPHA_APU' parameter for DPTC support

[Tim Van Patten (Code Review)]

Attention is currently required from: Jason Glenesk, Raul Rangel, Jason Nien, Matt DeVillier, Isaac Lee, Chris Wang, Martin Roth, Fred Reitberger, Felix Held.

Tim Van Patten has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/73123 )

Change subject: soc/amd/mendocino: Add new 'STT_ALPHA_APU' parameter for DPTC support
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Patch Set 1:

(4 comments)

File src/mainboard/google/skyrim/variants/winterhold/overridetree.cb:

https://review.coreboot.org/c/coreboot/+/73123/comment/fc0dfd24_d5d8cdc2 
PS1, Line 50: 	register "stt_alpha_apu_B" = "0x6666"
Since they are all the same value, remove all of these versions and just reference `stt_alpha_apu`. For example, see `vrm_current_limit_mA` which is reused for all thermal tables.

File src/soc/amd/mendocino/chip.h:

https://review.coreboot.org/c/coreboot/+/73123/comment/e15c61ac_06c18b8b 
PS1, Line 77: 	uint16_t stt_m1_tablet;
            : 	uint16_t stt_m2_tablet;
            : 	uint16_t stt_c_apu_tablet;
Why are these being added?

https://review.coreboot.org/c/coreboot/+/73123/comment/99f3f19d_de58bd71 
PS1, Line 80: 	uint16_t stt_alpha_apu_tablet;
Where is this being set?

https://review.coreboot.org/c/coreboot/+/73123/comment/859e07f1_b39fb190 
PS1, Line 91: 	uint16_t stt_alpha_apu_B;
Same as above. Unnecessary, so remove.