net: pass info struct via netdevice notifier

So far, only net_device * could be passed along with netdevice notifier
event. This patch provides a possibility to pass custom structure
able to provide info that event listener needs to know.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>

v2->v3: fix typo on simeth
	shortened dev_getter
	shortened notifier_info struct name
v1->v2: fix notifier_call parameter in call_netdevice_notifier()
Signed-off-by: David S. Miller <davem@davemloft.net>

net/xfrm/xfrm_policy.c

@@ -2784,7 +2784,7 @@ static void __net_init xfrm_dst_ops_init(struct net *net)
 
 static int xfrm_dev_event(struct notifier_block *this, unsigned long event, void *ptr)
 {
-	struct net_device *dev = ptr;
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 
 	switch (event) {
 	case NETDEV_DOWN: