modules/openid: remove unused $config from linkback.php.

git-svn-id: https://simplesamlphp.googlecode.com/svn/trunk@2838 44740490-163a-0410-bde0-09ae8108e29a

modules/openid/www/linkback.php

 <?php
 
-$config = SimpleSAML_Configuration::getInstance();
-
 /* Find the authentication state. */
 if (!array_key_exists('AuthState', $_REQUEST) || empty($_REQUEST['AuthState'])) {
 	throw new SimpleSAML_Error_BadRequest('Missing mandatory parameter: AuthState');