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/usb/hso.c b/drivers/net/usb/hso.c
index be0cc99..a6227f8 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -834,8 +834,6 @@
 	} else {
 		net->stats.tx_packets++;
 		net->stats.tx_bytes += skb->len;
-		/* And tell the kernel when the last transmit started. */
-		net->trans_start = jiffies;
 	}
 	dev_kfree_skb(skb);
 	/* we're done */
diff --git a/drivers/net/usb/kaweth.c b/drivers/net/usb/kaweth.c
index c4c334d..46890dc 100644
--- a/drivers/net/usb/kaweth.c
+++ b/drivers/net/usb/kaweth.c
@@ -856,7 +856,6 @@
 	{
 		kaweth->stats.tx_packets++;
 		kaweth->stats.tx_bytes += skb->len;
-		net->trans_start = jiffies;
 	}
 
 	spin_unlock_irq(&kaweth->device_lock);
diff --git a/drivers/net/usb/pegasus.c b/drivers/net/usb/pegasus.c
index 4183877..1cd17d2 100644
--- a/drivers/net/usb/pegasus.c
+++ b/drivers/net/usb/pegasus.c
@@ -808,7 +808,7 @@
 		break;
 	}
 
-	net->trans_start = jiffies;
+	net->trans_start = jiffies; /* prevent tx timeout */
 	netif_wake_queue(net);
 }
 
@@ -909,7 +909,6 @@
 	} else {
 		pegasus->stats.tx_packets++;
 		pegasus->stats.tx_bytes += skb->len;
-		net->trans_start = jiffies;
 	}
 	dev_kfree_skb(skb);