avformat/dvbsub: increase probe score

Ive not found a single false positive after some moderate testing with
probetest
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/dvbsub.c

@@ -60,7 +60,7 @@ static int dvbsub_probe(AVProbeData *p)
     }
 
     if (max_score > 5)
-        return AVPROBE_SCORE_EXTENSION/2;
+        return AVPROBE_SCORE_EXTENSION;
 
     return 0;
 }