net/dsa/hirschmann: Add missing of_node_get() in hellcreek_led_setup()

of_find_node_by_name() will decrease the refcount of its first arg and
we need a of_node_get() to keep refcount balance.

Fixes: 7d9ee2e ("net: dsa: hellcreek: Add PTP status LEDs")
Signed-off-by: Liang He <windhl@126.com>
Link: https://lore.kernel.org/r/20220622040621.4094304-1-windhl@126.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/hirschmann/hellcreek_ptp.c

@@ -300,6 +300,7 @@ static int hellcreek_led_setup(struct hellcreek *hellcreek)
 	const char *label, *state;
 	int ret = -EINVAL;
 
+	of_node_get(hellcreek->dev->of_node);
 	leds = of_find_node_by_name(hellcreek->dev->of_node, "leds");
 	if (!leds) {
 		dev_err(hellcreek->dev, "No LEDs specified in device tree!\n");