drm/i915: Make DRRS debugfs per-crtc/connector

Since I already broke anything that relied on the old contents
of the DRRS debugfs files might as well finish the breakage
and convert the files to be per-crtc/connector so we don't need
to have annoying code in igt to parse these.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221003113249.16213-4-ville.syrjala@linux.intel.com