If non-zero 'chunk_sectors' is passed in to blk_max_size_offset() that
override will be incorrectly ignored.
Old blk_max_size_offset() branching, prior to commit 3ee16db390,
must be used only if passed 'chunk_sectors' override is zero.
Fixes: 3ee16db390 ("dm: fix IO splitting")
Cc: stable@vger.kernel.org # 5.9
Reported-by: John Dorminy <jdorminy@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>