tests: fix #457

tests: fix #457

There are some limits on XFS:
major_max=511
minor_max=262143
see https://github.com/torvalds/linux/blob/master/fs/xfs/xfs_iops.c

if (S_ISCHR(mode) || S_ISBLK(mode)) {
    if (unlikely(!sysv_valid_dev(rdev) || MAJOR(rdev) & ~0x1ff))
        return -EINVAL;