tcp: no need to use acceptable for conn_request

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>