video_output: don't set render_now at all on late redisplay

It's already true by default.

src/video_output/video_output.c

@@ -1437,7 +1437,6 @@ static vlc_tick_t DisplayPicture(vout_thread_sys_t *vout)
             vlc_tick_t max_deadline = vlc_tick_now() + VOUT_REDISPLAY_DELAY;
             return __MIN(date_refresh, max_deadline);
         }
-        render_now = true;
     }
     else
     {