intel/isl: Add a missing assert in isl_tiling_get_intratile_offset_sa
Fixes: a4dafe1f "intel/isl: Make the offset helpers four dimensional" Acked-by:Ivan Briano <ivan.briano@intel.com> Reviewed-by:
Kenneth Graunke <kenneth@whitecape.org> Part-of: <mesa/mesa!11765> (cherry picked from commit eb7c28bf)