NFSv4.1: Use layout credentials for get_deviceinfo calls

This is not strictly needed, since get_deviceinfo is not allowed to
return NFS4ERR_ACCESS or NFS4ERR_WRONG_CRED, but lets do it anyway
for consistency with other pNFS operations.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c
index 22d1062..17ed87e 100644
--- a/fs/nfs/nfs4filelayout.c
+++ b/fs/nfs/nfs4filelayout.c
@@ -643,7 +643,8 @@
 	d = nfs4_find_get_deviceid(NFS_SERVER(lo->plh_inode)->pnfs_curr_ld,
 				   NFS_SERVER(lo->plh_inode)->nfs_client, id);
 	if (d == NULL) {
-		dsaddr = filelayout_get_device_info(lo->plh_inode, id, gfp_flags);
+		dsaddr = filelayout_get_device_info(lo->plh_inode, id,
+				lo->plh_lc_cred, gfp_flags);
 		if (dsaddr == NULL)
 			goto out;
 	} else