tcp: no need to use acceptable for conn_request

Since tcp_conn_request() always returns zero, there is no need to
keep the dead code. Remove it then.

Link: https://lore.kernel.org/netdev/CANn89iJwx9b2dUGUKFSV3PF=kN5o+kxz3A_fHZZsOS4AnXhBNw@mail.gmail.com/
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240213131205.4309-1-kerneljasonxing@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: JasonXing

net/ipv4/tcp_input.c

@@ -6623,7 +6623,6 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 	const struct tcphdr *th = tcp_hdr(skb);
 	struct request_sock *req;
 	int queued = 0;
-	bool acceptable;
 	SKB_DR(reason);
 
 	switch (sk->sk_state) {
@@ -6649,12 +6648,10 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 			 */
 			rcu_read_lock();
 			local_bh_disable();
-			acceptable = icsk->icsk_af_ops->conn_request(sk, skb) >= 0;
+			icsk->icsk_af_ops->conn_request(sk, skb);
 			local_bh_enable();
 			rcu_read_unlock();
 
-			if (!acceptable)
-				return 1;
 			consume_skb(skb);
 			return 0;
 		}