[XS] Change in libgfxinit[cros]: gma tgl: Pcode CDCLK_PREPARE_FOR_CHANGE is not mandatory

[Angel Pons (Code Review)]

Attention is currently required from: Angel Pons, Anil Kumar K, Dinesh Gehlot.

Angel Pons has posted comments on this change. ( https://review.coreboot.org/c/libgfxinit/+/82147?usp=email )

Change subject: gma tgl: Pcode CDCLK_PREPARE_FOR_CHANGE is not mandatory
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Patch Set 4: Code-Review+2

(2 comments)

Commit Message:

https://review.coreboot.org/c/libgfxinit/+/82147/comment/b6e31155_99501192 :
PS2, Line 10: BIOS Reset CPL and may fail when called too early.
> yes, it is related to romstage graphics init.

Would be nice to mention this in the commit message

File common/tigerlake/hw-gfx-gma-power_and_clocks.adb:

https://review.coreboot.org/c/libgfxinit/+/82147/comment/f9b1ad28_8ad6c55a :
PS4, Line 331: not Config.CPU_Alderlake
Would be nice to turn this into a dedicated config variable.