NFS: drop useless LIST_HEAD

Drop LIST_HEAD where the variable it declares has never
been used.

The semantic patch that fixes this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
identifier x;
@@
- LIST_HEAD(x);
  ... when != x
// </smpl>

Fixes: 0e20162e ("NFSv4.1 Use MDS auth flavor for data server connection")
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/nfs4client.c

@@ -151,7 +151,6 @@ static void
 nfs4_shutdown_ds_clients(struct nfs_client *clp)
 {
 	struct nfs4_ds_server *dss;
-	LIST_HEAD(shutdown_list);
 
 	while (!list_empty(&clp->cl_ds_clients)) {
 		dss = list_entry(clp->cl_ds_clients.next,