drm/amd/display: reject atomic commit if setting both plane and CRTC degamma

drm/amd/display: reject atomic commit if setting both plane and CRTC degamma

DC only has pre-blending degamma caps (plane/DPP) that is currently in
use for CRTC/post-blending degamma, so that we don't have HW caps to
perform plane and CRTC degamma at the same time. Reject atomic updates
when serspace sets both plane and CRTC degamma properties.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>