power: supply: rt9455_charger: 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/rt9455_charger.c

@@ -1593,7 +1593,7 @@ static const struct regmap_config rt9455_regmap_config = {
 static int rt9455_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 device *dev = &client->dev;
 	struct rt9455_info *info;
 	struct power_supply_config rt9455_charger_config = {};