pan/mdg: Vectorize vlut operations

pan/mdg: Vectorize vlut operations

total instructions in shared programs: 49462 -> 49458 (<.01%)
instructions in affected programs: 348 -> 344 (-1.15%)
helped: 2
HURT: 0

total bundles in shared programs: 25201 -> 25199 (<.01%)
bundles in affected programs: 142 -> 140 (-1.41%)
helped: 2
HURT: 0

total quadwords in shared programs: 40273 -> 40269 (<.01%)
quadwords in affected programs: 244 -> 240 (-1.64%)
helped: 2
HURT: 0

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5513>