Probe the GAMMA_LUT/GAMMA_LUT_SIZE props and utilize them when
the running with > 8bpc.

v2: s/sna_crtc_id/__sna_crtc_id/ in DBG since we have a sna_crtc
v3: Fix the vg "bluered" typo (Mario)
    This time I even build tested with vg support

Cc: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-and-tested-by: Mario Kleiner <mario.kleiner.de@gmail.com>