Remove unused variables from unit test method
Remove unused variables from unit test method

The method signature for _http_idp_input() in test_v3_federation.py
accepted all kwargs passed to it, and did some logic with them. It
turns out that nothing ever passes kwargs to that method, so I
removed that case and simplified the method signature.

Change-Id: I72b7e7fb29c10f51e174cbd2516ddd5610cedbda

ilay09/keystone,ilay09/keystone,openstack/keystone,mahak/keystone,rajalokan/keystone,rajalokan/keystone,ilay09/keystone,mahak/keystone,rajalokan/keystone,mahak/keystone,openstack/keystone,openstack/keystone