Update TfaTrustedBrowser.php

Closes #3393464

src/Plugin/TfaLogin/TfaTrustedBrowser.php

@@ -99,6 +99,7 @@ class TfaTrustedBrowser extends TfaBasePlugin implements TfaLoginInterface, TfaV
    * {@inheritdoc}
    */
   public function validateForm(array $form, FormStateInterface $form_state) {
+    return TRUE;
   }
 
   /**