IIO: si7020: Allocate correct amount of memory in devm_iio_device_alloc

Since only a pointer to struct i2c_client is stored in a private area
of IIO device created by the driver there's no need to allocate
sizeof(struct i2c_client) worth of storage.

Pushed to stable as this is linked to the revert patch previously.
Without this followup the original patch looks sensible.
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/humidity/si7020.c

@@ -126,7 +126,7 @@ static int si7020_probe(struct i2c_client *client,
 	/* Wait the maximum power-up time after software reset. */
 	msleep(15);
 
-	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*client));
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 	if (!indio_dev)
 		return -ENOMEM;