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

[Nico Huber (Code Review)]

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

Nico Huber 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: 
You can use `bool` and still have `0`/`1` in the devicetree, right?
I'd prefer that, seems easier to read.