compositor: use surface_set_size() in one more case

Fix one left-over case that directly assigned
weston_surface::width,height, and so missed view dirtying.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

src/compositor.c

@@ -1203,8 +1203,8 @@ weston_surface_set_size_from_buffer(struct weston_surface *surface)
 	}
 
 	if (surface->buffer_viewport.viewport_set) {
-		surface->width = surface->buffer_viewport.dst_width;
+		surface_set_size(surface, surface->buffer_viewport.dst_width,
-		surface->height = surface->buffer_viewport.dst_height;
+				 surface->buffer_viewport.dst_height);
 		return;
 	}