intel/ir/gen12: Update assert in brw_stage_has_packed_dispatch().

Confirmed no regressions after a full Piglit run on TGL with the
brw_fs_test_dispatch_packing() test enabled.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/intel/compiler/brw_compiler.h

@@ -1461,7 +1461,7 @@ brw_stage_has_packed_dispatch(ASSERTED const struct gen_device_info *devinfo,
     * to do a full test run with brw_fs_test_dispatch_packing() hooked up to
     * the NIR front-end before changing this assertion.
     */
-   assert(devinfo->gen <= 11);
+   assert(devinfo->gen <= 12);
 
    switch (stage) {
    case MESA_SHADER_FRAGMENT: {