irda: stop calling sk_prot->disconnect() on connection failure

The sk_prot is irda's own set of protocol handlers, so irda should
statically know what that function is anyway, without using an indirect
pointer.  And as it happens, we know *exactly* what that pointer is
statically: it's NULL, because irda doesn't define a disconnect
operation.

So calling that function is doubly wrong, and will just cause an oops.

Reported-by: Martin Lang <mlg.hessigheim@gmail.com>
Cc: Samuel Ortiz <samuel@sortiz.org>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

net/irda/af_irda.c

@@ -1064,8 +1064,6 @@ static int irda_connect(struct socket *sock, struct sockaddr *uaddr,
 
 	if (sk->sk_state != TCP_ESTABLISHED) {
 		sock->state = SS_UNCONNECTED;
-		if (sk->sk_prot->disconnect(sk, flags))
-			sock->state = SS_DISCONNECTING;
 		err = sock_error(sk);
 		if (!err)
 			err = -ECONNRESET;