Fix decoding of teletext in ps files (the zvbi decoder expects the full PES...

Fix decoding of teletext in ps files (the zvbi decoder expects the full PES packet, I haven't been able to test the telx.c decoder yet as I don't have any ps file with teletext subtitles available).

modules/demux/ps.c

@@ -382,7 +382,8 @@ static int Demux( demux_t *p_demux )
             p_sys->i_scr = -1;
 
             if( tk->b_seen && tk->es &&
-                !ps_pkt_parse_pes( p_pkt, tk->i_skip ) )
+                ( tk->fmt.i_codec == VLC_FOURCC('t','e','l','x') ||
+                  !ps_pkt_parse_pes( p_pkt, tk->i_skip ) ) )
             {
                 if( !b_new && !p_sys->b_have_pack && tk->fmt.i_cat == AUDIO_ES && p_pkt->i_pts > 0 )
                 {