[L] Change in coreboot[master]: mb/{skl,kbl}: Use true/false keywords for non-array dt options

[Erik van den Bogaert (Code Review)]

Attention is currently required from: Angel Pons, Felix Singer, Frans Hendriks, Jeremy Soller, Michał Żygowski, Nico Huber, Piotr Król, Sean Rhodes, Tim Crawford.

Erik van den Bogaert has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/75888?usp=email )

Change subject: mb/{skl,kbl}: Use true/false keywords for non-array dt options
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Patch Set 5: Code-Review+1