qxl: also notify the rendering is done when skipping it

Asynchronous handlers may be waiting for the graphic_hw_update_done() to
be called in this case too.

Fixes: 4d6316218 ("console: add graphic_hw_update_done()")
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210201201422.446552-3-marcandre.lureau@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hw/display/qxl-render.c

@@ -181,6 +181,7 @@ void qxl_render_update(PCIQXLDevice *qxl)
         qxl->mode == QXL_MODE_UNDEFINED) {
         qxl_render_update_area_unlocked(qxl);
         qemu_mutex_unlock(&qxl->ssd.lock);
+        graphic_hw_update_done(qxl->ssd.dcl.con);
         return;
     }