NFS: Use nfs4_destroy_server() to clean up NFS v4

I can use this function to return delegations and unset the pnfs layout
driver rather than continuing to do these things in the generic client.
With this change, we no longer need an nfs4_kill_super().

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index bd3a960..9a7a1b4 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -417,9 +417,8 @@
  * @sb: sb to process
  *
  */
-void nfs_super_return_all_delegations(struct super_block *sb)
+void nfs_server_return_all_delegations(struct nfs_server *server)
 {
-	struct nfs_server *server = NFS_SB(sb);
 	struct nfs_client *clp = server->nfs_client;
 	struct nfs_delegation *delegation;