net-next: remove useless union keyword

remove useless union keyword in rtable, rt6_info and dn_route.

Since there is only one member in a union, the union keyword isn't useful.

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/rxrpc/ar-peer.c b/net/rxrpc/ar-peer.c
index f0f85b0..9f1729b 100644
--- a/net/rxrpc/ar-peer.c
+++ b/net/rxrpc/ar-peer.c
@@ -64,8 +64,8 @@
 		return;
 	}
 
-	peer->if_mtu = dst_mtu(&rt->u.dst);
-	dst_release(&rt->u.dst);
+	peer->if_mtu = dst_mtu(&rt->dst);
+	dst_release(&rt->dst);
 
 	_leave(" [if_mtu %u]", peer->if_mtu);
 }