nfsd: drop useless LIST_HEAD

Drop LIST_HEAD where the variable it declares is never used.

This was introduced in c5c707f96f ("nfsd: implement pNFS
layout recalls"), but was not used even in that commit.

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

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

Fixes: c5c707f96f ("nfsd: implement pNFS layout recalls")
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4layouts.c

@@ -656,7 +656,6 @@ nfsd4_cb_layout_done(struct nfsd4_callback *cb, struct rpc_task *task)
 	struct nfsd_net *nn;
 	ktime_t now, cutoff;
 	const struct nfsd4_layout_ops *ops;
-	LIST_HEAD(reaplist);
 
 
 	switch (task->tk_status) {