iio:chemical:ccs811: Improve error reporting for problems during .remove()

Returning an error value in an i2c remove callback results in a generic
error message being emitted by the i2c core, but otherwise it doesn't
make a difference. The device goes away anyhow and the devm cleanups are
called.

So instead of triggering the generic i2c error message, emit a more
helpful message if a problem occurs and return 0 to suppress the generic
message.

This patch is a preparation for making i2c remove callbacks return void.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20220515155929.338656-5-u.kleine-koenig@pengutronix.deSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/chemical/ccs811.c

@@ -536,14 +536,20 @@ static int ccs811_remove(struct i2c_client *client)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
 	struct ccs811_data *data = iio_priv(indio_dev);
+	int ret;
 
 	iio_device_unregister(indio_dev);
 	iio_triggered_buffer_cleanup(indio_dev);
 	if (data->drdy_trig)
 		iio_trigger_unregister(data->drdy_trig);
 
-	return i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE,
-					 CCS811_MODE_IDLE);
+	ret = i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE,
+					CCS811_MODE_IDLE);
+	if (ret)
+		dev_warn(&client->dev, "Failed to power down device (%pe)\n",
+			 ERR_PTR(ret));
+
+	return 0;
 }
 
 static const struct i2c_device_id ccs811_id[] = {