power: supply: bq24257_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/bq24257_charger.c

@@ -959,7 +959,7 @@ static int bq24257_fw_probe(struct bq24257_device *bq)
 static int bq24257_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;
 	const struct acpi_device_id *acpi_id;
 	struct bq24257_device *bq;