net: pass changed flags along with NETDEV_CHANGE event

Use new netdevice notifier infrastructure to pass along changed flags.

Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>

v2->v3: shortened notifier_info struct name
Signed-off-by: David S. Miller <davem@davemloft.net>