Make intel_gpu_frequency complain about missing files
intel_gpu_frequency
tool tries to open /sys/class/drm/card?/gt_*_freq_mhz
and if any of those fail we just hard assert()
with no context, which is confusing at best.
We should provide some details about what operation has failed before exiting so we don't bamboozle the users.
See #54 (closed)