pNFS: Remove redundant smp_mb() from pnfs_init_lseg()

It's not visible yet, and won't be until after we grab the inode->i_lock.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/pnfs.c

@@ -341,7 +341,6 @@ pnfs_init_lseg(struct pnfs_layout_hdr *lo, struct pnfs_layout_segment *lseg,
 	INIT_LIST_HEAD(&lseg->pls_list);
 	INIT_LIST_HEAD(&lseg->pls_lc_list);
 	atomic_set(&lseg->pls_refcount, 1);
-	smp_mb();
 	set_bit(NFS_LSEG_VALID, &lseg->pls_flags);
 	lseg->pls_layout = lo;
 	lseg->pls_range = *range;