of: unittest: kmemleak in of_unittest_platform_populate()

kmemleak reports several memory leaks from devicetree unittest.
This is the fix for problem 2 of 5.

of_unittest_platform_populate() left an elevated reference count for
grandchild nodes (which are platform devices).  Fix the platform
device reference counts so that the memory will be freed.

Fixes: fb2caa50 ("of/selftest: add testcase for nodes with same name and address")
Reported-by: Erhard F. <erhard_f@mailbox.org>
Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>

drivers/of/unittest.c

@@ -1247,10 +1247,13 @@ static void __init of_unittest_platform_populate(void)
 
 	of_platform_populate(np, match, NULL, &test_bus->dev);
 	for_each_child_of_node(np, child) {
-		for_each_child_of_node(child, grandchild)
-			unittest(of_find_device_by_node(grandchild),
+		for_each_child_of_node(child, grandchild) {
+			pdev = of_find_device_by_node(grandchild);
+			unittest(pdev,
 				 "Could not create device for node '%pOFn'\n",
 				 grandchild);
+			of_dev_put(pdev);
+		}
 	}
 
 	of_platform_depopulate(&test_bus->dev);