Replace remaining occurances of av_free_packet with av_packet_unref

libavformat/libmodplug.c

@@ -325,7 +325,7 @@ static int modplug_read_packet(AVFormatContext *s, AVPacket *pkt)
 
     pkt->size = ModPlug_Read(modplug->f, pkt->data, AUDIO_PKT_SIZE);
     if (pkt->size <= 0) {
-        av_free_packet(pkt);
+        av_packet_unref(pkt);
         return pkt->size == 0 ? AVERROR_EOF : AVERROR(EIO);
     }
     return 0;