i2c: mux: ltc4306: simplify code to reach the adapter

struct i2c_client has a direct pointer to the adapter, no need to dig
it out of the struct device tree.

Suggested-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Peter Rosin <peda@axentia.se>

drivers/i2c/muxes/i2c-mux-ltc4306.c

@@ -208,7 +208,7 @@ MODULE_DEVICE_TABLE(of, ltc4306_of_match);
 
 static int ltc4306_probe(struct i2c_client *client)
 {
-	struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
+	struct i2c_adapter *adap = client->adapter;
 	const struct chip_desc *chip;
 	struct i2c_mux_core *muxc;
 	struct ltc4306 *data;