bonding: add/del secondary mac address callback

bonding: add/del secondary mac address callback

Type: feature

Add a callback to the bond device class which allows a secondary
mac address to be added/deleted.

The desired operation is performed on all the hardware interfaces
which belong to the bond interface. This allows virtual MAC
addresses to be used on bond interfaces without requiring the
hardware interfaces to have promiscuous mode enabled.

When a hardware interface is added or removed from a bond, if there
are any secondary MAC addresses configured on the bond, they are
added or removed from the hardware interface.

Change-Id: If9488078b4d7869ecc56ef6853f3cc9891211860
Signed-off-by: Matthew Smith <mgsmith@netgate.com>