amdrapl: add AMD RAPL energy/power telemetry driver

[afscoelho_gmail.com]

Summary

amdrapl exposes per-package and per-core energy from AMD RAPL MSRs via
sysctl. Sampled on demand at read time. Self-disarming overflow guard
bounds 32-bit counter wrap during read silence. Suspend/resume
re-baselines counters so reset folds no spurious delta into totals.

Power in milliwatts over measured interval. Fine-grained energy values
privileged-only: power side channel (PLATYPUS, CVE-2020-8694).

Binds to physical sockets/cores via cpu_get_pkg_id() and
cpu_get_core_id() -> socket-scoped or SMT-shared MSR sampled once per
real domain. Requires SMP. Wired into NOTES and module build.

Sponsored by: Advanced Micro Devices (AMD)
MFC after: 2 weeks
Signed-off-by: Andre Silva <[e-mail]>

[afscoelho_gmail.com]

Abandoning this duplicate review. The driver update has been moved to the original continued review D55603, which now sits on top of D57758 and D57759.