Synchonize devices multicast list
int __dev_mc_sync(struct net_device * dev, int (*sync) (struct net_device *, const unsigned char *), int (*unsync) (struct net_device *, const unsigned char *));
dev
device to sync
sync
function to call if address should be added
unsync
function to call if address should be removed
Add newly added addresses to the interface, and release addresses that have been deleted.