MDL-51259 mod_data: ratings of items not activated.

When selecting a rating method, the restrict rating
to items with dates would be automatically enabled if
not checked. This code brings the data module inline
with forum and glossary.

mod/data/lib.php

@@ -899,6 +899,11 @@ function data_add_instance($data, $mform = null) {
         $data->assessed = 0;
     }
 
+    if (empty($data->ratingtime) || empty($data->assessed)) {
+        $data->assesstimestart  = 0;
+        $data->assesstimefinish = 0;
+    }
+
     $data->timemodified = time();
 
     $data->id = $DB->insert_record('data', $data);