Remove faulty return when vobsub doesn't define a size.

Close #10111

modules/demux/mkv/matroska_segment_parse.cpp

@@ -1771,7 +1771,6 @@ int32_t matroska_segment_c::TrackInit( mkv_track_t * p_tk )
                 {
                     free( psz_buf );
                     msg_Warn( &sys.demuxer, "reading original frame size for vobsub failed" );
-                    return 1;
                 }
 
                 psz_start = strstr( psz_buf, "palette:" );