nir/lower_vec_to_movs: don't vectorize unsupports ops

nir/lower_vec_to_movs: don't vectorize unsupports ops

If the instruction being coalesced would be vectorized but the target
doesn't support vectorizing that op, skip coalescing.
Reuse the callbacks from alu_to_scalar to describe which ops should not
be vectorized.

Signed-off-by: Erico Nunes <nunes.erico@gmail.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6506>