gallium/aux/util: Trivial, we already have format use it

No need to dereference again, fixup for clarity.

Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Signed-off-by: Marek Olšák <marek.olsak@amd.com>

src/gallium/auxiliary/util/u_surface.c

@@ -397,7 +397,7 @@ util_clear_render_target(struct pipe_context *pipe,
          }
       }
       else {
-         util_pack_color(color->f, dst->format, &uc);
+         util_pack_color(color->f, format, &uc);
       }
 
       util_fill_box(dst_map, dst->format,