drm/i915/display/debugfs: New entry "DRRS capable" to i915_drrs_status

If the connected panel supports both DRRS & PSR, driver gives preference
to PSR ("DRRS enabled: no"). Even though the hardware supports DRRS,
IGT treats ("DRRS enabled: yes") as not capable.

Introduce a new entry "DRRS capable" to debugfs i915_drrs_status, so
that IGT will read the DRRS capability as "DRRS capable: yes".

Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem@intel.com>
Reviewed-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240221111223.2313692-1-bhanuprakash.modem@intel.com