fix regression by 8c43ba62('filesetup: align layout buffer')

fix regression by 8c43ba62('filesetup: align layout buffer')

8c43ba62('filesetup: align layout buffer') needs to use the same size
for fio_memalign() and fio_memfree().

If the size `bs' gets decreased while in the write(2) loop, the size
for freeing is smaller than it should be, and results in segfault
by dereferencing ->offset of the footer via irrelevant address somewhere
in user data.

Signed-off-by: Tomohiro Kusumi <tkusumi@tuxera.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>