ac/llvm: support vec2 on b2i16

Since radeonsi sets the alu_to_scalar callback, frontends like Rusticl
might end up generating vec2 b2i16. Support this just like it's done for
b2f16.

Fixes: d692d433f28 ("radeonsi: use nir_lower_alu_to_scalar correctly")
Signed-off-by: Karol Herbst <git@karolherbst.de>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23551>
1 file changed