Remove useless pass from methods in type_tunnel.py
Remove useless pass from methods in type_tunnel.py

The pass is useless because there is a docstring in the methods.
Generally considered as uncovered by coverage tool.

Change-Id: Id1275c51e9adb865a3da9f0db007f3092b55b140

adelina-t/neutron,klmitch/neutron,cloudbase/neutron,silenci/neutron,dims/neutron,mmnelemane/neutron,MaximNevrov/neutron,glove747/liberty-neutron,sasukeh/neutron,cisco-openstack/neutron,shahbazn/neutron,swdream/neutron,jacknjzhou/neutron,watonyweng/neutron,wolverineav/neutron,mattt416/neutron,suneeth51/neutron,bgxavier/neutron,suneeth51/neutron,SamYaple/neutron,mandeepdhami/neutron,wolverineav/neutron,eonpatapon/neutron,jacknjzhou/neutron,dhanunjaya/neutron,bigswitch/neutron,neoareslinux/neutron,paninetworks/neutron,jumpojoy/neutron,skyddv/neutron,igor-toga/local-snat,paninetworks/neutron,klmitch/neutron,chitr/neutron,asgard-lab/neutron,glove747/liberty-neutron,chitr/neutron,jerryz1982/neutron,silenci/neutron,bigswitch/neutron,vivekanand1101/neutron,noironetworks/neutron,javaos74/neutron,javaos74/neutron,openstack/neutron,mahak/neutron,barnsnake351/neutron,sebrandon1/neutron,yanheven/neutron,cloudbase/neutron,dims/neutron,MaximNevrov/neutron,swdream/neutron,eonpatapon/neutron,dhanunjaya/neutron,sebrandon1/neutron,bgxavier/neutron,mandeepdhami/neutron,barnsnake351/neutron,noironetworks/neutron,wenhuizhang/neutron,neoareslinux/neutron,apporc/neutron,huntxu/neutron,NeCTAR-RC/neutron,jumpojoy/neutron,huntxu/neutron,apporc/neutron,openstack/neutron,openstack/neutron,watonyweng/neutron,shahbazn/neutron,wenhuizhang/neutron,NeCTAR-RC/neutron,jerryz1982/neutron,adelina-t/neutron,eayunstack/neutron,skyddv/neutron,sasukeh/neutron,mahak/neutron,takeshineshiro/neutron,mahak/neutron,igor-toga/local-snat,vivekanand1101/neutron,SamYaple/neutron,asgard-lab/neutron,mmnelemane/neutron,mattt416/neutron,eayunstack/neutron,takeshineshiro/neutron,JianyuWang/neutron,JianyuWang/neutron,cisco-openstack/neutron,yanheven/neutron