pan/mdg: Defer nir_fuse_io_16 until after opts

Sometimes DCE/etc can opt out things that would force 32-bit, so this is
worthwhile.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5513>
1 file changed