[FIX] survey: fix survey "previous page" button

This commit fixes the "back button" that appears when the user is taking the
survey, allowing to go back to previous pages or questions.

There was a typo in the name of the parameter.

Task 2152223

closes odoo/odoo#43003

Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/survey/static/src/js/survey_form.js

@@ -105,7 +105,7 @@ publicWidget.registry.SurveyFormWidget = publicWidget.Widget.extend({
     _onSubmit: function (event) {
         event.preventDefault();
         if ($(event.currentTarget).val() === 'previous') {
-            this._submitForm({'previous_id': $(event.currentTarget).data('previousId')});
+            this._submitForm({'previous_page_id': $(event.currentTarget).data('previousPageId')});
         } else {
             this._submitForm({});
         }