ipv4/route: arg delay is useless in rt_cache_flush()

Since route cache deletion (89aef8921bfbac22f), delay is no
more used. Remove it.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 77e87af..4780045 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -1225,7 +1225,7 @@
 	switch (event) {
 	case NETDEV_CHANGEADDR:
 		neigh_changeaddr(&arp_tbl, dev);
-		rt_cache_flush(dev_net(dev), 0);
+		rt_cache_flush(dev_net(dev));
 		break;
 	default:
 		break;