drm/i915: Split up intel_color_init()

intel_color_init() does both device level and crtc level stuff.
Split it up accordingly.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220929071521.26612-3-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>