power: supply: max17042_battery: Add external_power_changed callback

If our supplier changes status, chances are we've changed status too,
let any listeners know about this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>

drivers/power/supply/max17042_battery.c

@@ -429,6 +429,11 @@ static int max17042_property_is_writeable(struct power_supply *psy,
 	return ret;
 }
 
+static void max17042_external_power_changed(struct power_supply *psy)
+{
+	power_supply_changed(psy);
+}
+
 static int max17042_write_verify_reg(struct regmap *map, u8 reg, u32 value)
 {
 	int retries = 8;
@@ -917,6 +922,7 @@ static const struct power_supply_desc max17042_psy_desc = {
 	.get_property	= max17042_get_property,
 	.set_property	= max17042_set_property,
 	.property_is_writeable	= max17042_property_is_writeable,
+	.external_power_changed	= max17042_external_power_changed,
 	.properties	= max17042_battery_props,
 	.num_properties	= ARRAY_SIZE(max17042_battery_props),
 };