iio:chemical:atlas: Switch from CONFIG_PM guards to pm_ptr() etc

Letting the compiler remove these functions when the kernel is built
without CONFIG_PM 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.
Acked-by: Matt Ranostay <matt.ranostay@konsulko.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20220130193147.279148-49-jic23@kernel.org

drivers/iio/chemical/atlas-sensor.c

@@ -737,7 +737,6 @@ static int atlas_remove(struct i2c_client *client)
 	return atlas_set_powermode(data, 0);
 }
 
-#ifdef CONFIG_PM
 static int atlas_runtime_suspend(struct device *dev)
 {
 	struct atlas_data *data =
@@ -753,18 +752,16 @@ static int atlas_runtime_resume(struct device *dev)
 
 	return atlas_set_powermode(data, 1);
 }
-#endif
 
 static const struct dev_pm_ops atlas_pm_ops = {
-	SET_RUNTIME_PM_OPS(atlas_runtime_suspend,
-			   atlas_runtime_resume, NULL)
+	RUNTIME_PM_OPS(atlas_runtime_suspend, atlas_runtime_resume, NULL)
 };
 
 static struct i2c_driver atlas_driver = {
 	.driver = {
 		.name	= ATLAS_DRV_NAME,
 		.of_match_table	= atlas_dt_ids,
-		.pm	= &atlas_pm_ops,
+		.pm	= pm_ptr(&atlas_pm_ops),
 	},
 	.probe		= atlas_probe,
 	.remove		= atlas_remove,