hlsdemux: Always succeed the LATENCY event

Upstream and our internal source is irrelevant for the latency
and we don't want the LATENCY event to ever fail.

ext/hls/gsthlsdemux.c

@@ -552,6 +552,13 @@ gst_hls_demux_src_event (GstPad * pad, GstObject * parent, GstEvent * event)
       gst_event_unref (event);
       return TRUE;
     }
+    case GST_EVENT_LATENCY:{
+      /* Upstream and our internal source are irrelevant
+       * for latency, and we should not fail here to
+       * configure the latency */
+      gst_event_unref (event);
+      return TRUE;
+    }
     default:
       break;
   }