iio: adc: exynos_adc: fix OF populate on driver rebind

Since commit c6e126de43e7 ("of: Keep track of populated platform
devices") child devices will not be created by of_platform_populate()
if the devices had previously been deregistered individually so that the
OF_POPULATED flag is still set in the corresponding OF nodes.

Switch to using of_platform_depopulate() instead of open coding so that
the child devices are created if the driver is rebound.

Fixes: c6e126de43e7 ("of: Keep track of populated platform devices")
Cc: [e-mail] # 3.16
Signed-off-by: Johan Hovold <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/exynos_adc.c

···
 	ADC_CHANNEL(9, "adc9"),
 };
 
-static int exynos_adc_remove_devices(struct device *dev, void *c)
-{
-	struct platform_device *pdev = to_platform_device(dev);
-
-	platform_device_unregister(pdev);
-
-	return 0;
-}
-
 static int exynos_adc_probe(struct platform_device *pdev)
 {
 	struct exynos_adc *info = NULL;
···
 	return 0;
 
 err_of_populate:
-	device_for_each_child(&indio_dev->dev, NULL,
-				exynos_adc_remove_devices);
+	of_platform_depopulate(&indio_dev->dev);
 	iio_device_unregister(indio_dev);
 err_irq:
 	free_irq(info->irq, info);
···
 	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 	struct exynos_adc *info = iio_priv(indio_dev);
 
-	device_for_each_child(&indio_dev->dev, NULL,
-				exynos_adc_remove_devices);
+	of_platform_depopulate(&indio_dev->dev);
 	iio_device_unregister(indio_dev);
 	free_irq(info->irq, info);
 	if (info->data->exit_hw)