Fix promiscuous mode with if_octm:
o) The MAC set must occur before the multicast list is set up as the former
will enable the CAM unconditionally, while promiscuous mode disables it, so if promiscuous mode is to be set this must occur after the MAC is programmed.
o) The multicast list must be set up unconditionally as even if flags have
not changed, if the interface has gone through a reinitialization, the state of the CAM as changed by the MAC initialization could be incorrect.
o) Call octm_init when flags change, even if the interface is already running.