[admin] remove two-step authentication

lang/en/lang_takelogin.php

@@ -6,6 +6,8 @@ $lang_takelogin = array
 	'std_login_fail' => "Login failed!",
 	'std_account_disabled' => "This account has been disabled.",
 	'std_user_account_unconfirmed' => "The account has not been verified yet. If you didn't receive the confirmation email, try to <a href='confirm_resend.php'><b>reseed it</b></a>.",
+    'std_require_two_step_code' => 'Require two-step authentication code.',
+    'std_invalid_two_step_code' => 'Invalid two-step authentication code.',
 );
 
 ?>