iio: adc: palmas_gpadc: fix NULL dereference on rmmod

Calling dev_to_iio_dev() on a platform device pointer is undefined and
will make adc NULL.
Signed-off-by: Patrik Dahlström <risca@dalakolonin.se>
Link: https://lore.kernel.org/r/20230313205029.1881745-1-risca@dalakolonin.seSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/palmas_gpadc.c

@@ -639,7 +639,7 @@ static int palmas_gpadc_probe(struct platform_device *pdev)
 
 static int palmas_gpadc_remove(struct platform_device *pdev)
 {
-	struct iio_dev *indio_dev = dev_to_iio_dev(&pdev->dev);
+	struct iio_dev *indio_dev = dev_get_drvdata(&pdev->dev);
 	struct palmas_gpadc *adc = iio_priv(indio_dev);
 
 	if (adc->wakeup1_enable || adc->wakeup2_enable)