xfs/107: fix formatting failures

xfs/107: fix formatting failures

Zorro Lang reported that the _scratch_mkfs_sized call in the new xfs/107
fstest sometimes fails on more exotic storage due to insufficient log
size on account of raid stripes, etc.   These are side effects of the
filesystem being too small.

Change the filesystem size to 256M to avoid these problems, and change
the allocstale parameters to use the same file size (16M) as before.
Given that ALLOCSP produces stale disk contents pretty quickly this
shouldn't affect the test runtime too much.

Reported-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>