drm/drm_plane: track color mgmt changes per plane

We will add color mgmt properties to DRM planes in the next patches and
we want to track when one of this properties change to define atomic
commit behaviors. Using a similar approach from CRTC color props, we set
a color_mgmt_changed boolean whenever a plane color prop changes.

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