iio:chemical:sgp30: Use local variable dev to simplify code

This cleans up the code at bit, but is primarily here as a precusor
to the next patch. I've only done this for the two functions
which use the dev pointer repeatedly.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Andreas Brauchli <andreas.brauchli@sensirion.com>
Link: https://lore.kernel.org/r/20200910173242.621168-27-jic23@kernel.org

drivers/iio/chemical/sgp30.c

@@ -409,6 +409,7 @@ static int sgp_read_raw(struct iio_dev *indio_dev,
 static int sgp_check_compat(struct sgp_data *data,
 			    unsigned int product_id)
 {
+	struct device *dev = &data->client->dev;
 	const struct sgp_version *supported_versions;
 	u16 ix, num_fs;
 	u16 product, generation, major, minor;
@@ -416,21 +417,20 @@ static int sgp_check_compat(struct sgp_data *data,
 	/* driver does not match product */
 	generation = SGP_VERS_GEN(data);
 	if (generation != 0) {
-		dev_err(&data->client->dev,
+		dev_err(dev,
 			"incompatible product generation %d != 0", generation);
 		return -ENODEV;
 	}
 
 	product = SGP_VERS_PRODUCT(data);
 	if (product != product_id) {
-		dev_err(&data->client->dev,
-			"sensor reports a different product: 0x%04hx\n",
+		dev_err(dev, "sensor reports a different product: 0x%04hx\n",
 			product);
 		return -ENODEV;
 	}
 
 	if (SGP_VERS_RESERVED(data))
-		dev_warn(&data->client->dev, "reserved bit is set\n");
+		dev_warn(dev, "reserved bit is set\n");
 
 	/* engineering samples are not supported: no interface guarantees */
 	if (SGP_VERS_ENG_BIT(data))
@@ -456,8 +456,7 @@ static int sgp_check_compat(struct sgp_data *data,
 		    minor >= supported_versions[ix].minor)
 			return 0;
 	}
-	dev_err(&data->client->dev, "unsupported sgp version: %d.%d\n",
-		major, minor);
+	dev_err(dev, "unsupported sgp version: %d.%d\n", major, minor);
 
 	return -ENODEV;
 }
@@ -499,17 +498,18 @@ static const struct of_device_id sgp_dt_ids[] = {
 static int sgp_probe(struct i2c_client *client,
 		     const struct i2c_device_id *id)
 {
+	struct device *dev = &client->dev;
 	struct iio_dev *indio_dev;
 	struct sgp_data *data;
 	const struct of_device_id *of_id;
 	unsigned long product_id;
 	int ret;
 
-	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 	if (!indio_dev)
 		return -ENOMEM;
 
-	of_id = of_match_device(sgp_dt_ids, &client->dev);
+	of_id = of_match_device(sgp_dt_ids, dev);
 	if (of_id)
 		product_id = (unsigned long)of_id->data;
 	else
@@ -541,9 +541,9 @@ static int sgp_probe(struct i2c_client *client,
 
 	sgp_init(data);
 
-	ret = devm_iio_device_register(&client->dev, indio_dev);
+	ret = devm_iio_device_register(dev, indio_dev);
 	if (ret) {
-		dev_err(&client->dev, "failed to register iio device\n");
+		dev_err(dev, "failed to register iio device\n");
 		return ret;
 	}