Bridge: Always send NETDEV_CHANGEADDR up on br MAC change.

This ensures the neighbor entries associated with the bridge
dev are flushed, also invalidating the associated cached L2 headers.

This means we br_add_if/br_del_if ports to implement hand-over and
not wind up with bridge packets going out with stale MAC.

This means we can also change MAC of port device and also not wind
up with bridge packets going out with stale MAC.

This builds on Stephen Hemminger's patch, also handling the br_del_if
case and the port MAC change case.

Cc: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Andrei Warkentin <andreiw@motorola.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>