iio:dac:vf610: Switch from CONFIG_PM_SLEEP guards to pm_sleep_ptr() etc

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.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20220130193147.279148-18-jic23@kernel.org

drivers/iio/dac/vf610_dac.c

@@ -242,7 +242,6 @@ static int vf610_dac_remove(struct platform_device *pdev)
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
 static int vf610_dac_suspend(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
@@ -268,9 +267,9 @@ static int vf610_dac_resume(struct device *dev)
 
 	return 0;
 }
-#endif
 
-static SIMPLE_DEV_PM_OPS(vf610_dac_pm_ops, vf610_dac_suspend, vf610_dac_resume);
+static DEFINE_SIMPLE_DEV_PM_OPS(vf610_dac_pm_ops, vf610_dac_suspend,
+				vf610_dac_resume);
 
 static struct platform_driver vf610_dac_driver = {
 	.probe          = vf610_dac_probe,
@@ -278,7 +277,7 @@ static struct platform_driver vf610_dac_driver = {
 	.driver         = {
 		.name   = "vf610-dac",
 		.of_match_table = vf610_dac_match,
-		.pm     = &vf610_dac_pm_ops,
+		.pm     = pm_sleep_ptr(&vf610_dac_pm_ops),
 	},
 };
 module_platform_driver(vf610_dac_driver);