drm/i915: Clean up ilk/icl pipe/output CSC programming

drm/i915: Clean up ilk/icl pipe/output CSC programming

We have far too much messy duplicated code in the
pipe/output CSC programming. Simply provide two functions
(ilk_update_pipe_csc() and icl_update_output_csc()) to
program the relevant CSC registers. The desired offsets
and coefficients are passed in as parameters.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190218193137.22914-5-ville.syrjala@linux.intel.com
Reviewed-by: Uma Shankar <uma.shankar@intel.com>