drm/i915: Clean up cherryview_load_luts()

I like my functions simple, so split up the low level bits from
cherryview_load_luts() into separate functions. Also rename the
whole thing to chv_load_luts() to match the new world order.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190408121815.30142-1-ville.syrjala@linux.intel.com


Reviewed-by: Swati Sharma <swati2.sharma@intel.com>