Add ACPI CPPC support for AMD CPUs/APUs

[coldsprinkles]

Modern AMD CPUs/APUs expose ACPI CPPC interfaces that allow the operating system to manage CPU frequency and performance in a fine-grained, collaborative way.
this kext currently relies on legacy P-state control, which is coarse and limits efficiency and performance tuning.
Implementing CPPC in this kext would bring feature parity with Linux’s amd_pstate driver and deliver major benefits for responsiveness, battery life, and thermal management.

For my case, enabling CPPC on Linux let my CPU downclock to ~400 MHz at idle, which drastically reduced idle power draw.
As a result, my laptop’s battery life jumped from about 3 hours to over 6 hours during light usage like browsing, coding, and note-taking — all while keeping the system cooler and quieter without sacrificing responsiveness during bursts.

Please do look into this!