It is used as size argument of ff_canopus_parse_info_tag, which uses it
as size argument to bytestream2_init, which only supports sizes up to
INT_MAX.
Changing it's type to unsigned simplifies the check.
Reviewed-by: Vittorio Giovara <vittorio.giovara@gmail.com>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>