Change in coreboot[master]: drivers/intel/gma: Support IGD Opregion 2.1

[Angel Pons (Code Review)]

Attention is currently required from: Nico Huber, Krishna Prabhakaran, Furquan Shaikh, Maulik V Vaghela, Selma Bensaid, Subrata Banik, Meera Ravindranath, Patrick Rudolph.
Angel Pons has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/52758 )

Change subject: drivers/intel/gma: Support IGD Opregion 2.1
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Patch Set 14:

(1 comment)

File src/drivers/intel/gma/Kconfig:

https://review.coreboot.org/c/coreboot/+/52758/comment/e57a9460_3b10ac82 
PS13, Line 105: INTEL_GMA_OPREGION_2_0
> If we have to keep both 2.0 and 2.1 can we find a way to make 2.1 as the default? I think all future platforms would want to select 2.1, so it is better to keep that as the default.

Hmmm, can we try to not rely on implicit defaults? I'd rather have each platform explicitly select the Opregion version it is meant to be used with.

Yes, I know that what I suggested in https://review.coreboot.org/c/coreboot/+/52758/comment/bd09c08d_c09e941a/ selects 2.0 by default, but it's easy to rework the Kconfig options so that nothing is selected by default. I'd do this in another commit (which would also select 2.0 on ADL), then update ADL to use 2.1 in a third commit.