[XS] Change in coreboot[main]: mb/google/rex/var/karis: Set pen detect pin to NC for non-stylus sku

[Subrata Banik (Code Review)]

Attention is currently required from: David Wu, Dinesh Gehlot, Eran Mitrani, Kapil Porwal, Tarun, Tyler Wang.

Subrata Banik has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/79213?usp=email )

Change subject: mb/google/rex/var/karis: Set pen detect pin to NC for non-stylus sku
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Patch Set 1: Code-Review+2