avformat/ty: Remove write-only array and variable

avformat/ty: Remove write-only array and variable

Up until now, the TiVo demuxer parse an array of SEQ entries, yet it has
never ever made any use of them. In fact, parse_master, the function
parsing said table, only influenced the outside world in three ways: Via
an excessive amount of error message in case a certain parameter is not
what it expected; via an allocation (the aforementioned write-only
array); and by setting a certain parameter (ty->cur_chunk_pos), but that
parameter is always overwritten before it is used (it is overwritten
in get_chunk() on success and if get_chunk() fails, the error is
returned to the caller anyway). So remove the array and the function
used to parse it.

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>