trelay: handle netdevice events correctly

trelay: handle netdevice events correctly

Since v3.11, netdevice notification data are of type
"struct netdev_notifier_info". Handle it as such!

This should fix a critical bug in which devices are unable get released
because trelay does not release resources in response to UNREGISTER
event spamming the log with something like:

unregister_netdevice: waiting for eth0.1 to become free. Usage count = 1

Signed-off-by: Ali MJ Al-Nasrawy <alimjalnasrawy@gmail.com>
(cherry picked from commit 77cfc0739d30c1282f7de24d2ec086d244e34bb7)