af_key: replace BUG_ON on WARN_ON in net_exit hook

Signed-off-by: NVasily Averin <vvs@virtuozzo.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/key/af_key.c

@@ -3845,7 +3845,7 @@ static void __net_exit pfkey_net_exit(struct net *net)
 	struct netns_pfkey *net_pfkey = net_generic(net, pfkey_net_id);
 
 	pfkey_exit_proc(net);
-	BUG_ON(!hlist_empty(&net_pfkey->table));
+	WARN_ON(!hlist_empty(&net_pfkey->table));
 }
 
 static struct pernet_operations pfkey_net_ops = {