cvdsub: fix the codec ID on the packetizer output

All other decoders that also double as a packetizer do this.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/codec/cvdsub.c

@@ -139,6 +139,7 @@ static int PacketizerOpen( vlc_object_t *p_this )
 
     if( DecoderOpen( p_this ) != VLC_SUCCESS ) return VLC_EGENERIC;
 
+    p_dec->fmt_out.i_codec = VLC_CODEC_CVD;
     p_dec->p_sys->b_packetizer = true;
 
     return VLC_SUCCESS;