pNFS: Fix an unused variable warning in pnfs_roc_get_barrier

{

	struct nfs_inode *nfsi = NFS_I(ino);

	struct pnfs_layout_hdr *lo;

	nfs4_stateid stateid;

	u32 current_seqid;

	spin_lock(&ino->i_lock);

	 * a barrier, we choose the worst-case barrier.

	 */

	*barrier = current_seqid + atomic_read(&lo->plh_outstanding);

	stateid = lo->plh_stateid;

	spin_unlock(&ino->i_lock);

}