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/de600.c b/drivers/net/de600.c
index 6b13f4f..23a6539 100644
--- a/drivers/net/de600.c
+++ b/drivers/net/de600.c
@@ -166,8 +166,8 @@
 	int	i;
 
 	if (free_tx_pages <= 0) {	/* Do timeouts, to avoid hangs. */
-		tickssofar = jiffies - dev->trans_start;
-		if (tickssofar < 5)
+		tickssofar = jiffies - dev_trans_start(dev);
+		if (tickssofar < HZ/20)
 			return NETDEV_TX_BUSY;
 		/* else */
 		printk(KERN_WARNING "%s: transmit timed out (%d), %s?\n", dev->name, tickssofar, "network cable problem");