avformat/mpeg: Remove unnecessary av_packet_unref()

Forgotten in 6a67d518.
Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavformat/mpeg.c

@@ -961,7 +961,7 @@ static int vobsub_read_packet(AVFormatContext *s, AVPacket *pkt)
         if (ret < 0) {
             if (pkt->size) // raise packet even if incomplete
                 break;
-            goto fail;
+            return ret;
         }
         to_read = ret & 0xffff;
         new_pos = avio_tell(pb);
@@ -978,7 +978,7 @@ static int vobsub_read_packet(AVFormatContext *s, AVPacket *pkt)
 
         ret = av_grow_packet(pkt, to_read);
         if (ret < 0)
-            goto fail;
+            return ret;
 
         n = avio_read(pb, pkt->data + (pkt->size - to_read), to_read);
         if (n < to_read)
@@ -986,10 +986,6 @@ static int vobsub_read_packet(AVFormatContext *s, AVPacket *pkt)
     } while (total_read < psize);
 
     return 0;
-
-fail:
-    av_packet_unref(pkt);
-    return ret;
 }
 
 static int vobsub_read_seek(AVFormatContext *s, int stream_index,