s390/qeth: don't bother updating the last-tx time

As the documentation for netif_trans_update() says, netdev_start_xmit()
already updates the last-tx time after every good xmit. So don't
duplicate that effort.

One odd case is that qeth_flush_buffers() also gets called from our
TX completion handler, to flush out any partially filled buffer when
we switch the queue to non-packing mode. But as the TX completion
handler will _always_ wake the txq, we don't have to worry about
the TX watchdog there.
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/s390/net/qeth_core_main.c

@@ -3371,7 +3371,6 @@ static void qeth_flush_buffers(struct qeth_qdio_out_q *queue, int index,
 	}
 
 	QETH_TXQ_STAT_ADD(queue, bufs, count);
-	netif_trans_update(queue->card->dev);
 	qdio_flags = QDIO_FLAG_SYNC_OUTPUT;
 	if (atomic_read(&queue->set_pci_flags_count))
 		qdio_flags |= QDIO_FLAG_PCI_OUT;