This is no longer used, the -o nobarrier is handled by
BTRFS_MOUNT_NOBARRIER.  Remove the flag.
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>