enable F402 check for flake8
enable F402 check for flake8

The change removes the shadowed loop variables and enables F402 checking

Change-Id: I015797feec463ffb0b5e97229a6ec2c9a41df9de
Partial-Bug: 1329017

Gitweijie/first_project,CiscoSystems/networking-cisco,Gitweijie/first_project,cisco-openstack/networking-cisco,Tehsmash/networking-cisco,cisco-openstack/networking-cisco,openstack/networking-cisco,Tehsmash/networking-cisco,noironetworks/networking-cisco,openstack/networking-cisco,nikolay-fedotov/networking-cisco,hareeshpc/networking-cisco,CiscoSystems/networking-cisco,hareeshpc/networking-cisco,noironetworks/networking-cisco