xfs/447: fix typo

Fix a trivial typo that keeps barfing up:
./tests/xfs/447: line 60: /dev_null: Read-only file system

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>
1 file changed