bonding: remove useless updating of slave->dev->last_rx

Now that all the logic is handled via last_arp_rx, we don't need to use
last_rx.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
CC: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -1115,9 +1115,6 @@ static rx_handler_result_t bond_handle_frame(struct sk_buff **pskb)
 	slave = bond_slave_get_rcu(skb->dev);
 	bond = slave->bond;
 
-	if (bond->params.arp_interval)
-		slave->dev->last_rx = jiffies;
-
 	recv_probe = ACCESS_ONCE(bond->recv_probe);
 	if (recv_probe) {
 		ret = recv_probe(skb, bond, slave);

include/linux/netdevice.h

@@ -1312,13 +1312,7 @@ struct net_device {
 /*
  * Cache lines mostly used on receive path (including eth_type_trans())
  */
-	unsigned long		last_rx;	/* Time of last Rx
-						 * This should not be set in
-						 * drivers, unless really needed,
-						 * because network stack (bonding)
-						 * use it if/when necessary, to
-						 * avoid dirtying this cache line.
-						 */
+	unsigned long		last_rx;	/* Time of last Rx */
 
 	/* Interface address info used in eth_type_trans() */
 	unsigned char		*dev_addr;	/* hw address, (before bcast