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/depca.c b/drivers/net/depca.c
index a88300a0..38d4d9e 100644
--- a/drivers/net/depca.c
+++ b/drivers/net/depca.c
@@ -921,7 +921,7 @@
 	STOP_DEPCA;
 	depca_init_ring(dev);
 	LoadCSRs(dev);
-	dev->trans_start = jiffies;
+	dev->trans_start = jiffies; /* prevent tx timeout */
 	netif_wake_queue(dev);
 	InitRestartDepca(dev);
 }
@@ -954,7 +954,6 @@
 			outw(CSR0, DEPCA_ADDR);
 			outw(INEA | TDMD, DEPCA_DATA);
 
-			dev->trans_start = jiffies;
 			dev_kfree_skb(skb);
 		}
 		if (TX_BUFFS_AVAIL)