intel/nir: rerun lower_tex if it lowers something

intel/nir: rerun lower_tex if it lowers something

nir_lower_tex can lower tg4 coords into tg4 offset which on DG2+ we
also need to lower into constant offsets.

Unfortunately the nir_lower_tex pass is not able to lower the
instructions it itself generates, so the easy fix for when
nir_lower_tex lowers tg4 coords into tg4 offsets is to rerun the pass.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/9735
Cc: mesa-stable
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Tested-by: Yiwei Zhang <zzyiwei@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25015>