flv: use default pad query

We need to chain up unknown queries to the default query handler instead of
blindly forwarding them. In this case it caused the caps query to be forwarded
to the upstream typefind and return the wrong type for the audio/video pad.

gst/flv/gstflvdemux.c

@@ -3064,7 +3064,7 @@ gst_flv_demux_query (GstPad * pad, GstObject * parent, GstQuery * query)
     }
     case GST_QUERY_LATENCY:
     default:
-      res = gst_pad_peer_query (demux->sinkpad, query);
+      res = gst_pad_query_default (pad, parent, query);
       break;
   }