Change in coreboot[master]: soc/intel/tigerlake/apci: Only use SCM for ChromeOS

[Tim Wawrzynczak (Code Review)]

Attention is currently required from:  Felix Singer, Sean Rhodes, Patrick Rudolph.
Tim Wawrzynczak has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/58798 )

Change subject: soc/intel/tigerlake/apci: Only use SCM for ChromeOS
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Patch Set 9: Code-Review+2

(3 comments)

Patchset:

PS5:
> Unfortunately, this has turned out to be Part 1 of 2 as D3cold is refusing to turn off. […]

To be clear: you are trying to disable d3cold support for the TBT ports?

Patchset:

PS9:
> Alder Lake might need doing, don't have on to test though..

Very likely, the TBT support is basically the same.

PS9: 
Seems OK for now, but let's keep an eye on how many different "configuration" options we need in this file... we may want to add new Kconfig options instead of CHROMEOS everywhere.