connector: remove duplicated code in cn_call_callback()

There were a couple of patches fixing the same bug that
results in duplicated err = 0; assignment.
The patch removes one of them.
Signed-off-by: NAlexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/connector/connector.c

@@ -139,7 +139,6 @@ static int cn_call_callback(struct sk_buff *skb)
 	spin_unlock_bh(&dev->cbdev->queue_lock);
 
 	if (cbq != NULL) {
-		err = 0;
 		cbq->callback(msg, nsp);
 		kfree_skb(skb);
 		cn_queue_release_callback(cbq);