net: trans_start cleanups

Now that core network takes care of trans_start updates, dont do it
in drivers themselves, if possible. Drivers can avoid one cache miss
(on dev->trans_start) in their start_xmit() handler.

Exceptions are NETIF_F_LLTX drivers

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/natsemi.c b/drivers/net/natsemi.c
index 9250bf6..2a17b50 100644
--- a/drivers/net/natsemi.c
+++ b/drivers/net/natsemi.c
@@ -1905,7 +1905,7 @@
 	spin_unlock_irq(&np->lock);
 	enable_irq(dev->irq);
 
-	dev->trans_start = jiffies;
+	dev->trans_start = jiffies; /* prevent tx timeout */
 	np->stats.tx_errors++;
 	netif_wake_queue(dev);
 }
@@ -2119,8 +2119,6 @@
 	}
 	spin_unlock_irqrestore(&np->lock, flags);
 
-	dev->trans_start = jiffies;
-
 	if (netif_msg_tx_queued(np)) {
 		printk(KERN_DEBUG "%s: Transmit frame #%d queued in slot %d.\n",
 			dev->name, np->cur_tx, entry);