inet: Create and use rt{,6}_get_peer_create().

There's a lot of places that open-code rt{,6}_get_peer() only because
they want to set 'create' to one.  So add an rt{,6}_get_peer_create()
for their sake.

There were also a few spots open-coding plain rt{,6}_get_peer() and
those are transformed here as well.

Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp_ipv4.c

@@ -1832,9 +1832,7 @@ struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it)
 		peer = inet_getpeer_v4(net, inet->inet_daddr, 1);
 		*release_it = true;
 	} else {
-		if (!rt->peer)
-			rt_bind_peer(rt, inet->inet_daddr, 1);
-		peer = rt->peer;
+		peer = rt_get_peer_create(rt, inet->inet_daddr);
 		*release_it = false;
 	}