net: marvell: Fix refcounting bugs in prestera_port_sfp_bind()

In prestera_port_sfp_bind(), there are two refcounting bugs:
(1) we should call of_node_get() before of_find_node_by_name() as
it will automaitcally decrease the refcount of 'from' argument;
(2) we should call of_node_put() for the break of the iteration
for_each_child_of_node() as it will automatically increase and
decrease the 'child'.

Fixes: 52323ef ("net: marvell: prestera: add phylink support")
Signed-off-by: Liang He <windhl@126.com>
Reviewed-by: Yevhen Orlov <yevhen.orlov@plvision.eu>
Link: https://lore.kernel.org/r/20220921133245.4111672-1-windhl@126.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: windhl

drivers/net/ethernet/marvell/prestera/prestera_main.c

@@ -368,6 +368,7 @@ static int prestera_port_sfp_bind(struct prestera_port *port)
 	if (!sw->np)
 		return 0;
 
+	of_node_get(sw->np);
 	ports = of_find_node_by_name(sw->np, "ports");
 
 	for_each_child_of_node(ports, node) {
@@ -417,6 +418,7 @@ static int prestera_port_sfp_bind(struct prestera_port *port)
 	}
 
 out:
+	of_node_put(node);
 	of_node_put(ports);
 	return err;
 }