ac/llvm: add disable_aniso_single_level abi

ac/llvm: add disable_aniso_single_level abi

RADV use dri option to enabled this for some apps, but it's
done in nir lower currently. I'm afraid it still needs this
option to handle the non-uniform case as desc is loaded in
llvm.

radeonsi always enable this for bind-textures.

radeonsi will lower all bind-textures to bindless-textures,
and only bind-textures use desc index, so add this abi for
bindless desc index path.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18666>