drm/i915: Reorder 12.4 lut udw vs. ldw functions

Satisfy my ocd and define ilk_lut_12p4_ldw() before ilk_lut_12p4_udw().
That is the order all the other similar functions use.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221114153732.11773-6-ville.syrjala@linux.intel.com