NFSv4: Do not call rpciod_down() before call to destroy_nfsv4_state()

The reason is that the idmapper cleanup may call flush_workqueue() on
rpciod_workqueue.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/inode.c

@@ -2025,10 +2025,11 @@ static void nfs4_kill_super(struct super_block *sb)
 
 	if (server->client != NULL && !IS_ERR(server->client))
 		rpc_shutdown_client(server->client);
-	rpciod_down();		/* release rpciod */
 
 	destroy_nfsv4_state(server);
 
+	rpciod_down();
+
 	kfree(server->hostname);
 	kfree(server);
 }