avformat/vqf: Return 0 on success in read_packet

Demuxers are not supposed to return the size of the packet read.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavformat/vqf.c

@@ -259,7 +259,7 @@ static int vqf_read_packet(AVFormatContext *s, AVPacket *pkt)
     c->last_frame_bits = pkt->data[size+1];
     c->remaining_bits  = (size << 3) - c->frame_bit_len + c->remaining_bits;
 
-    return size+2;
+    return 0;
 }
 
 static int vqf_read_seek(AVFormatContext *s,