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: 7d9ee2e8ff15 ("net: dsa: hellcreek: Add PTP status LEDs")
Signed-off-by: Liang He <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/dsa/hirschmann/hellcreek_ptp.c

···
 	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");