fstests: rename RENAME_WHITEOUT test on fs no enough space

This's a regression test for linux 6b4b8e6b4ad8 ("ext4: fix bug for
rename with RENAME_WHITEOUT"). Rename a file with RENAME_WHITEOUT
flag might cause corruption when there's not enough space to
complete this renaming operation.

Signed-off-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Sun Ke <sunke32@huawei.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>