Change in coreboot[master]: mb/system76/gaze15: Add System76 Gazelle 15

[Tim Crawford (Code Review)]

Attention is currently required from: Martin Roth, Jeremy Soller, Paul Menzel, Angel Pons.
Tim Crawford has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/47822 )

Change subject: mb/system76/gaze15: Add System76 Gazelle 15
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Patch Set 9:

(1 comment)

File src/mainboard/system76/gaze15/gpio.c:

https://review.coreboot.org/c/coreboot/+/47822/comment/680efd8c_c86aa24e 
PS8, Line 98: //
> I simply booted the board without any GPIO config and then checked against vendor firmware values an […]

This is taking me a while to do, since I don't know what changes are significant between the vendor firmware, leaving them unset, and what we set. Almost every GPIO is configured differently in vendor firmware. If I'm parsing it right, vendor firmware configures IOSTERM, but IOSTANDBY isn't enabled on CML.