powerd: Introduce Energy/Performance Preferences (EPP) support

[osa]

Summary

Add initial support for Energy/Performance Preferences (EPP) for powerd(8).

The powerd(8) currently doesn't support AMD Collaborative Processor Performance Control (CPPC) or Intel Speed Shift Technology via hwpstate_amd(4), manual is missing, and hwpstate_intel(4) correspondingly.

Test Plan

I tested these changes on my X1 Carbon Gen5 laptop. I have no access to AMD hardware to test the changes.

[osa]

According to the [[ https://wiki.FreeBSD.org/Phabricator | Phabricator article on FreeBSD Wiki ]]it's necessary using the format-patch -U999999 to generate a patch.

git checkout powerd-epp
git format-patch -U999999 --stdout main > powerd-epp.diff

[osa]

Updated version of the patch.