[TCP]: Remove superflushious skb == write_queue_tail() check

Needed can only be more strict than what was checked by the
earlier common case check for non-tail skbs, thus
cwnd_len <= needed will never match in that case anyway.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_output.c

@@ -1057,7 +1057,7 @@ static unsigned int tcp_mss_split_point(struct sock *sk, struct sk_buff *skb,
 
 	needed = min(skb->len, window);
 
-	if (skb == tcp_write_queue_tail(sk) && cwnd_len <= needed)
+	if (cwnd_len <= needed)
 		return cwnd_len;
 
 	return needed - needed % mss_now;