drm/i915/drrs: Refactor CPU transcoder DRRS check

drm/i915/drrs: Refactor CPU transcoder DRRS check

Rename cpu_transcoder_has_drrs() to intel_cpu_transcoder_has_drrs() and
move it to intel_drrs.[ch].

V2:
 - Move helpers to intel_drrs.[ch] (Jani)
 - Fix commit message (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Cc: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240228055502.2857819-1-bhanuprakash.modem@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>