Change in coreboot[master]: drivers/intel/gma: hook up GMA for Skylake+

[Matt DeVillier (Code Review)]

Matt DeVillier has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/39638 )

Change subject: drivers/intel/gma: hook up GMA for Skylake+
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Patch Set 15:

now that CB:32549 and CB:39731 have been merged, you can rebase on top of CB:39878, and then simply add the default brightness controls to the DSDT and the default GMA panel to the devicetree for each of these boards, and they will be fully hooked up.

also, commit subject needs to be reworded at this point