Minor fixes for Intel Xe cards + Memory frequency

[Steve-Tech]

Hi, this PR makes the following changes:

• Fixes Intel Arc Pro B60: power*_crit is reported as max power while power*_cap is 200 W #493
• Add max GPU memory frequency
  • For i915, this only seems to appear in the backport drivers: https://github.com/intel-gpu/intel-gpu-i915-backports/blob/88e15eff7c9ce9eb3941333088d38cf571960cfd/drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c#L903-L935
  • For Xe, this only seems to be available for 'Ponte Vecchio' data center GPUs: https://lore.kernel.org/all/20240109110418.2065101-1-sujaritha.sundaresan@intel.com/
• Partially Fix Intel iGPU, xe kernel driver: nvtop reports cur_freq (requested frequency) instead of act_freq (actual frequency) #450
  • Implement perf events, for more reliable measurement of the GPU frequency, however this now also requires CAP_PERFMON.
  • The underlying cur_freq vs act_freq is still present without CAP_PERFMON, however act_freq frequently returns 0, so I've left cur_freq for now.

I have a question:

• Intel only exposes the max memory frequency, is it okay to use this for mem_clock_speed so that it gets displayed, or would you prefer I use mem_clock_speed_max?

Thanks,
Steve