soreuseport: do not export reuseport_add_sock()

reuseport_add_sock() is not used from a module,
no need to export it.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/sock_reuseport.c

@@ -129,7 +129,6 @@ int reuseport_add_sock(struct sock *sk, struct sock *sk2)
 
 	return 0;
 }
-EXPORT_SYMBOL(reuseport_add_sock);
 
 static void reuseport_free_rcu(struct rcu_head *head)
 {