drm/i915: Expose crtc CTM property on ilk/snb

The ilk/snb code is internally fully capable of handling the
CTM property, so expose it.

Note that we still choose not to expose DEGAMMA_LUT though.
The hardware is capable if degamma or gamma, but not both
simultanously due to lack of the split gamma mode. Exposing
both LUTs might encourage userspace to try enabling both
at the same time.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230413164916.4221-3-ville.syrjala@linux.intel.com


Reviewed-by: Uma Shankar <uma.shankar@intel.com>