mech_driver_v2: remove update_security_group work around
mech_driver_v2: remove update_security_group work around

Depends-On: I5a27d1d218a0be4fae6f9740559bbbf773518821
Change-Id: I30b366afe1f1597e006cacaa2b171441ecd49676

openstack/networking-odl,openstack/networking-odl,openstack/networking-odl