l2_multi: Simplify initialization
l2_multi: Simplify initialization

We now use core.listen_to_dependencies() to handle event setup.

pthien92/sdn,pthien92/sdn,MurphyMc/pox,pthien92/sdn,noxrepo/pox,MurphyMc/pox,pthien92/sdn,noxrepo/pox,MurphyMc/pox,MurphyMc/pox,noxrepo/pox,pthien92/sdn,noxrepo/pox,MurphyMc/pox