gallium/util: Move the Z/S handling to the outside of get_tile().

This lets us drop the special case for S8_UINT, and makes our read_4 path
just like other callers.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5728>
1 file changed