gallium: replace old PIPE_FORMAT_U_S8 with PIPE_FORMAT_S8_UNORM

src/gallium/drivers/softpipe/sp_tile_cache.c

@@ -168,7 +168,7 @@ sp_tile_cache_set_surface(struct softpipe_tile_cache *tc,
       tc->depth_stencil = (ps->format == PIPE_FORMAT_S8Z24_UNORM ||
                            ps->format == PIPE_FORMAT_Z16_UNORM ||
                            ps->format == PIPE_FORMAT_Z32_UNORM ||
-                           ps->format == PIPE_FORMAT_U_S8);
+                           ps->format == PIPE_FORMAT_S8_UNORM);
    }
 }