iio: health: afe4403: 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.  Replace it with spi
functions to get the correct iio_dev.
Signed-off-by: Alison Schofield <amsfield22@gmail.com>
Acked-by: Andrew F. Davis <afd@ti.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/health/afe4403.c

@@ -422,7 +422,7 @@ MODULE_DEVICE_TABLE(of, afe4403_of_match);
 
 static int __maybe_unused afe4403_suspend(struct device *dev)
 {
-	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct iio_dev *indio_dev = spi_get_drvdata(to_spi_device(dev));
 	struct afe4403_data *afe = iio_priv(indio_dev);
 	int ret;
 
@@ -443,7 +443,7 @@ static int __maybe_unused afe4403_suspend(struct device *dev)
 
 static int __maybe_unused afe4403_resume(struct device *dev)
 {
-	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct iio_dev *indio_dev = spi_get_drvdata(to_spi_device(dev));
 	struct afe4403_data *afe = iio_priv(indio_dev);
 	int ret;