regulator: act8865-regulator: switch psy_cfg from of_node to fwnode

In order to remove .of_node from the power_supply_config struct,
use .fwnode instead.

Link: https://lore.kernel.org/r/20250430-psy-core-convert-to-fwnode-v2-1-f9643b958677@collabora.com
Reviewed-by: Hans de Goede <hansg@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

Author: sre

drivers/regulator/act8865-regulator.c

@@ -643,7 +643,7 @@ static int act8600_charger_probe(struct device *dev, struct regmap *regmap)
 	struct power_supply *charger;
 	struct power_supply_config cfg = {
 		.drv_data = regmap,
-		.of_node = dev->of_node,
+		.fwnode = dev_fwnode(dev),
 	};
 
 	charger = devm_power_supply_register(dev, &act8600_charger_desc, &cfg);