iio: adc: palmas_gpadc: retrieve a valid iio_dev in suspend/resume

The suspend/resume functions were using dev_to_iio_dev() to get
the iio_dev. That only works on IIO dev's.  Use dev_get_drvdata()
for a platform device to get the correct iio_dev.
Signed-off-by: Alison Schofield <amsfield22@gmail.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/adc/palmas_gpadc.c

@@ -775,7 +775,7 @@ static int palmas_adc_wakeup_reset(struct palmas_gpadc *adc)
 
 static int palmas_gpadc_suspend(struct device *dev)
 {
-	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct palmas_gpadc *adc = iio_priv(indio_dev);
 	int wakeup = adc->wakeup1_enable || adc->wakeup2_enable;
 	int ret;
@@ -798,7 +798,7 @@ static int palmas_gpadc_suspend(struct device *dev)
 
 static int palmas_gpadc_resume(struct device *dev)
 {
-	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct palmas_gpadc *adc = iio_priv(indio_dev);
 	int wakeup = adc->wakeup1_enable || adc->wakeup2_enable;
 	int ret;