Set DC plane with user degamma LUT or predefined TF from driver-specific
plane color properties. If plane and CRTC degamma are set in the same
time, plane degamma has priority.  That means, we only set CRTC degamma
if we don't have plane degamma LUT or TF to configure. We return -EINVAL
if we don't have plane degamma settings, so we can continue and check
CRTC degamma.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Joshua Ashton <joshua@froggi.es>
Signed-off-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>