TreeModel.test compile fix

for 2b19081cb0

Change-Id: I0b93014602a8a960d9357017bf3b3b096aa2b37c
Reviewed-by: hjk <hjk@theqtcompany.com>

tests/auto/utils/treemodel/tst_treemodel.cpp

@@ -47,7 +47,7 @@ private slots:
 static int countLevelItems(TreeItem *base, int level)
 {
     int n = 0;
-    foreach (TreeItem *item, base->model()->untypedItemsAtLevel(level, base)) {
+    foreach (TreeItem *item, UntypedTreeLevelItems(base, level)) {
         Q_UNUSED(item);
         ++n;
     }