power: supply: max17040_battery: simplify getting the adapter of a client

We have a dedicated pointer for that, so use it. Much easier to read and
less computation involved.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/max17040_battery.c

@@ -193,7 +193,7 @@ static const struct power_supply_desc max17040_battery_desc = {
 static int max17040_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
-	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
+	struct i2c_adapter *adapter = client->adapter;
 	struct power_supply_config psy_cfg = {};
 	struct max17040_chip *chip;