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/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index 434b93e..1e5fdd3 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -1091,7 +1091,7 @@
 	dev->mincount = 0;
 
 	dprintk("%s: dev_id: %s\n", __func__, dev->dev_id.data);
-	rc = nfs4_proc_getdeviceinfo(server, dev);
+	rc = nfs4_proc_getdeviceinfo(server, dev, NULL);
 	dprintk("%s getdevice info returns %d\n", __func__, rc);
 	if (rc) {
 		rv = ERR_PTR(rc);