[FIX] payment: Cannot add a new card from My Account portal

Steps to reproduce the bug:

Setup Authorize.net test account, then go to My Account from portal
and select "Manage your Payment Methods" and add a new card.

Bug:

It raised "Please fill all the inputs required."

opw:782716

addons/payment/static/src/js/payment_form.js

@@ -209,11 +209,11 @@ odoo.define('payment.payment_form', function (require) {
                     if (element.dataset.isRequired) {
                         if (element.value.length === 0) {
                             $(element).closest('div.form-group').addClass('has-error');
+                            empty_inputs = true;
                         }
                         else {
                             $(element).closest('div.form-group').removeClass('has-error');
                         }
-                        empty_inputs = true;
                     }
                 });