[M] Change in coreboot[main]: tree: Use boolean for dptf_enable

[Elyes Haouas (Code Review)]

Attention is currently required from: Dinesh Gehlot, Eran Mitrani, Eric Lai, Frans Hendriks, Jakub Czapiga, Jayvik Desai, Jonathon Hall, Kapil Porwal, Lean Sheng Tan, Maxim, Michał Żygowski, Nick Vaccaro, Nico Huber, Piotr Król, Pranava Y N, Rishika Raj, Subrata Banik, Tarun, Werner Zeh.

Elyes Haouas has posted comments on this change by Elyes Haouas. ( https://review.coreboot.org/c/coreboot/+/84161?usp=email )

Change subject: tree: Use boolean for dptf_enable
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Patch Set 1:

(1 comment)

Patchset:

PS1:
> I prefer true/false. It reduce ambiguity and potential errors and it prepare for modern C.  […]

while on it, please see https://review.coreboot.org/c/coreboot/+/83909/6 when you have time