[S] Change in coreboot[main]: soc/intel: Add config to use S3 over S0ix

[Tim Crawford (Code Review)]

Attention is currently required from: Arthur Heymans, Dinesh Gehlot, Eran Mitrani, Kapil Porwal, Nick Vaccaro, Tarun.

Tim Crawford has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/79631?usp=email )

Change subject: soc/intel: Add config to use S3 over S0ix
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Patch Set 2:

(1 comment)

Commit Message:

https://review.coreboot.org/c/coreboot/+/79631/comment/8835c17b_1c364512 :
PS2, Line 11: indicating to the OS that S3
            : suspend is the preferred sleep method.
The description for the flag is:
> A one informs OSPM that the platform is able to
> achieve power savings in S0 similar to or better
> than those typically achieved in S3. In effect,
> when this bit is set it indicates that the system
> will achieve no power benefit by making a sleep
> transition to S3.

which I read as "tell the OS to prefer modern suspend over S3".
> If you don't set it the OS cannot suspend that way.

Windows probably has no means to control which is used, but Linux can override which is used by `/sys/power/mem_sleep`. But Linux also seems to always claim s2idle support, even when `s0ix_enable` is not set, so I'm not sure how it's determining that.