iio:adc:exynos_adc: Switch from CONFIG_PM_SLEEP guards to pm_sleep_ptr()

Letting the compiler remove these functions when the kernel is built
without CONFIG_PM_SLEEP support is simpler and less error prone than the
use of #ifdef based config guards.

Removing instances of this approach from IIO also stops them being
copied into new drivers.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20220130193147.279148-12-jic23@kernel.org

drivers/iio/adc/exynos_adc.c

@@ -968,7 +968,6 @@ static int exynos_adc_remove(struct platform_device *pdev)
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
 static int exynos_adc_suspend(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
@@ -1001,10 +1000,8 @@ static int exynos_adc_resume(struct device *dev)
 
 	return 0;
 }
-#endif
 
-static SIMPLE_DEV_PM_OPS(exynos_adc_pm_ops,
-			exynos_adc_suspend,
+static DEFINE_SIMPLE_DEV_PM_OPS(exynos_adc_pm_ops, exynos_adc_suspend,
 				exynos_adc_resume);
 
 static struct platform_driver exynos_adc_driver = {
@@ -1013,7 +1010,7 @@ static struct platform_driver exynos_adc_driver = {
 	.driver		= {
 		.name	= "exynos-adc",
 		.of_match_table = exynos_adc_match,
-		.pm	= &exynos_adc_pm_ops,
+		.pm	= pm_sleep_ptr(&exynos_adc_pm_ops),
 	},
 };