iio:adc:palmas_gpadc: 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.

In this case SIMPLE_DEV_PM_OPS() could have been used previously.
Now we have DEFINE_SIMPLE_DEV_PM_OPS() which also deals with letting
the compiler remove the structure and functions so use that instead.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20220130193147.279148-13-jic23@kernel.org

drivers/iio/adc/palmas_gpadc.c

@@ -653,7 +653,6 @@ static int palmas_gpadc_remove(struct platform_device *pdev)
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
 static int palmas_adc_wakeup_configure(struct palmas_gpadc *adc)
 {
 	int adc_period, conv;
@@ -822,12 +821,9 @@ static int palmas_gpadc_resume(struct device *dev)
 
 	return 0;
 };
-#endif
 
-static const struct dev_pm_ops palmas_pm_ops = {
-	SET_SYSTEM_SLEEP_PM_OPS(palmas_gpadc_suspend,
-				palmas_gpadc_resume)
-};
+static DEFINE_SIMPLE_DEV_PM_OPS(palmas_pm_ops, palmas_gpadc_suspend,
+				palmas_gpadc_resume);
 
 static const struct of_device_id of_palmas_gpadc_match_tbl[] = {
 	{ .compatible = "ti,palmas-gpadc", },
@@ -840,7 +836,7 @@ static struct platform_driver palmas_gpadc_driver = {
 	.remove = palmas_gpadc_remove,
 	.driver = {
 		.name = MOD_NAME,
-		.pm = &palmas_pm_ops,
+		.pm = pm_sleep_ptr(&palmas_pm_ops),
 		.of_match_table = of_palmas_gpadc_match_tbl,
 	},
 };