net/bonding: emit address change event also in bond_release

commit 7d26bb103c4 "bonding: emit event when bonding changes MAC" didn't
take care to emit the NETDEV_CHANGEADDR event in bond_release, where bonding
actually changes the mac address (to all zeroes). As a result the neighbours
aren't deleted by the core networking code (which does so upon getting that
event).

Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>