Remove stray details checks from GET_ASSETS

The details attribute is store in get_assets_data->get.details. These
checks on get_assets_data->details are probably copy-paste errors from
GET_INFO. This works in GET_INFO because GET_INFO explicitly sets
details alongside get.details.

As a result the DETAILS element has never been returned from
GET_ASSETS. It's also missing from the docs.

Similarly, ROUTES is only returned from GET_ASSETS when an id
attribute is given, regardless of the value of the details attribute.

src/gmp.c

@@ -11905,7 +11905,7 @@ handle_get_assets (gmp_parser_t *gmp_parser, GError **error)
                                       (&details));
           cleanup_iterator (&details);
 
-          if (get_assets_data->details || get_assets_data->get.id)
+          if (get_assets_data->get.id)
             {
               routes_xml = host_routes_xml (asset);
               g_string_append (result, routes_xml);
@@ -11923,9 +11923,6 @@ handle_get_assets (gmp_parser_t *gmp_parser, GError **error)
     }
   cleanup_iterator (&assets);
 
-  if (get_assets_data->details == 1)
-    SEND_TO_CLIENT_OR_FAIL ("<details>1</details>");
-
   filtered = get_assets_data->get.id
               ? 1
               : asset_count (&get_assets_data->get);