Fix eventlog filtering (#14136)

Was sending device_id = 0 for all devices when it should have been device_id = null

includes/html/common/eventlog.inc.php

@@ -35,7 +35,7 @@ var eventlog_grid = $("#eventlog").bootgrid({
     post: function ()
     {
         return {
-            device: "' . (int) ($vars['device']) . '",
+            device: ' . (empty($vars['device']) ? 'null' : (int) $vars['device']) . ',
             eventtype: "' . addcslashes($vars['eventtype'], '"') . '",
         };
     },