drm/i915: Reject YCbCr output with degamma+gamma on pre-icl

Since the pipe CSC sits between the degamma and gamma LUTs there
is no way to make us it for RGB->YCbCr conversion when both LUTs
are also active. Simply reject such combos.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221026113906.10551-10-ville.syrjala@linux.intel.com


Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>