Remove unused code in common/neutron.py
Remove unused code in common/neutron.py

This remove a line of code that is never executed, and if it were
to be executed, is incorrect, since the variable doesn't exist.

This is a follow up to 78e689e5390acf0d18b433c05495628012466c61.

Change-Id: Ic6085c8c070539ca383d0625a1c44ab9e31e1527

openstack/ironic,openstack/ironic