Remove usage of deprecated module_name model option introduced in 1c0c879b.

django/contrib/admin/templates/admin/change_form.html

@@ -70,7 +70,7 @@
     <script type="text/javascript">
         (function($) {
             $(document).ready(function() {
-                $('form#{{ opts.module_name }}_form :input:visible:enabled:first').focus()
+                $('form#{{ opts.model_name }}_form :input:visible:enabled:first').focus()
             });
         })(django.jQuery);
     </script>