avformat/dvdvideodec: don't allow seeking beyond dvdnav reported duration

There is no reason to accept timestamp values beyond what dvdnav
reported as the duration of the title.

Signed-off-by: Marth64 <marth64@proxyid.net>

libavformat/dvdvideodec.c

@@ -1743,7 +1743,7 @@ static int dvdvideo_read_seek(AVFormatContext *s, int stream_index, int64_t time
     if ((flags & AVSEEK_FLAG_BYTE))
         return AVERROR(ENOSYS);
 
-    if (timestamp < 0)
+    if (timestamp < 0 || timestamp > s->duration)
         return AVERROR(EINVAL);
 
     if (!c->seek_warned) {