xen: netfront: explicitly generate arp_notify event after migration.

Use newly introduced netif_notify_peers() method to ensure a gratuitous ARP is
generated after a migration.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Stephen Hemminger <shemminger@linux-foundation.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Cc: xen-devel@lists.xensource.com
Cc: stable@kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/xen-netfront.c

@@ -1621,6 +1621,7 @@ static void backend_changed(struct xenbus_device *dev,
 		if (xennet_connect(netdev) != 0)
 			break;
 		xenbus_switch_state(dev, XenbusStateConnected);
+		netif_notify_peers(netdev);
 		break;
 
 	case XenbusStateClosing: