of: unittest: Run overlay apply/revert sequence three times

Run the test for the overlay apply/revert sequence three times, to
test if there are unbalanced of_node_put() calls causing reference
counts to become negative.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Link: https://lore.kernel.org/r/a9fb4[e-mail]
Signed-off-by: Rob Herring <[e-mail]>

drivers/of/unittest.c

···
 static void __init of_unittest_overlay(void)
 {
 	struct device_node *bus_np = NULL;
+	unsigned int i;
 
 	if (platform_driver_register(&unittest_driver)) {
 		unittest(0, "could not register unittest driver\n");
···
 	of_unittest_overlay_2();
 	of_unittest_overlay_3();
 	of_unittest_overlay_4();
-	of_unittest_overlay_5();
+	for (i = 0; i < 3; i++)
+		of_unittest_overlay_5();
 	of_unittest_overlay_6();
 	of_unittest_overlay_8();