mesa/st: bump param reservation to 28

now d3d12 is hitting it, so here we go

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16872>

src/mesa/state_tracker/st_glsl_to_nir.cpp

@@ -479,7 +479,7 @@ st_glsl_to_nir_post_opts(struct st_context *st, struct gl_program *prog,
     * storage is only associated with the original parameter list.
     * This should be enough for Bitmap and DrawPixels constants.
     */
-   _mesa_ensure_and_associate_uniform_storage(st->ctx, shader_program, prog, 20);
+   _mesa_ensure_and_associate_uniform_storage(st->ctx, shader_program, prog, 28);
 
    st_set_prog_affected_state_flags(prog);