compositor-drm: Never lift solid surfaces to planes

This will never work, so don't even try to do it.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

libweston/compositor-drm.c

@@ -3357,6 +3357,9 @@ drm_output_propose_state(struct weston_output *output_base,
 		if (ev->output_mask != (1u << output->base.id))
 			force_renderer = true;
 
+		if (!ev->surface->buffer_ref.buffer)
+			force_renderer = true;
+
 		/* Ignore views we know to be totally occluded. */
 		pixman_region32_init(&clipped_view);
 		pixman_region32_intersect(&clipped_view,