avformat/mpegts: adjust probe score for low check_count

Fixes mis-detection of tiff as mpegts
Fixes Ticket5565
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 00c4861f)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/mpegts.c

@@ -2462,8 +2462,10 @@ static int mpegts_probe(AVProbeData *p)
 
     ff_dlog(0, "TS score: %d %d\n", sumscore, maxscore);
 
-    if        (check_count >= CHECK_COUNT && sumscore > 6) {
+    if        (check_count > CHECK_COUNT && sumscore > 6) {
         return AVPROBE_SCORE_MAX   + sumscore - CHECK_COUNT;
+    } else if (check_count >= CHECK_COUNT && sumscore > 6) {
+        return AVPROBE_SCORE_MAX/2 + sumscore - CHECK_COUNT;
     } else if (check_count >= CHECK_COUNT && maxscore > 6) {
         return AVPROBE_SCORE_MAX/2 + sumscore - CHECK_COUNT;
     } else if (sumscore > 6) {