fix banner placements

contrib/templates/default/ukko.mustache

@@ -33,10 +33,10 @@
       {{/threads}}
       </div>
       <script type="text/javascript" src="{{prefix}}static/nntpchan.js">
-        document.onload = function() {
+
           var e = document.getElementById("nntpchan_banner");
           nntpchan_inject_banners(e, "{{prefix}}");
-        }
+
     </script>
   </body>
 </html>