tcp: get rid of __tcp_add_write_queue_tail()

This helper is only used from tcp_add_write_queue_tail(), and does
not make the code more readable.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/tcp.h

@@ -1716,14 +1716,9 @@ static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
 	return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
 }
 
-static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
-{
-	__skb_queue_tail(&sk->sk_write_queue, skb);
-}
-
 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
 {
-	__tcp_add_write_queue_tail(sk, skb);
+	__skb_queue_tail(&sk->sk_write_queue, skb);
 
 	/* Queue it, remembering where we must start sending. */
 	if (sk->sk_write_queue.next == skb)