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>

drivers/net/arm/ep93xx_eth.c

@@ -374,8 +374,6 @@ static int ep93xx_xmit(struct sk_buff *skb, struct net_device *dev)
 				skb->len, DMA_TO_DEVICE);
 	dev_kfree_skb(skb);
 
-	dev->trans_start = jiffies;
-
 	spin_lock_irq(&ep->tx_pending_lock);
 	ep->tx_pending++;
 	if (ep->tx_pending == TX_QUEUE_ENTRIES)