Remove unused variable assignment

This variable was assigned a value and then later assigned a new
value without ever being read in between, so the first assignment
had no affect.

Change-Id: I535776f5aa7b634375df23a4efae7e29d6e3d008

keystone/token/controllers.py

@@ -83,8 +83,6 @@ class Auth(controller.V2Controller):
             raise exception.ValidationError(attribute='auth',
                                             target='request body')
 
-        auth_token_data = None
-
         if "token" in auth:
             # Try to authenticate using a token
             auth_info = self._authenticate_token(