iio:light:ltr501: 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>
Cc: Maslov Dmitry <maslovdmitry@seeed.cc>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20220130193147.279148-24-jic23@kernel.org

drivers/iio/light/ltr501.c

@@ -1611,7 +1611,6 @@ static int ltr501_remove(struct i2c_client *client)
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
 static int ltr501_suspend(struct device *dev)
 {
 	struct ltr501_data *data = iio_priv(i2c_get_clientdata(
@@ -1627,9 +1626,8 @@ static int ltr501_resume(struct device *dev)
 	return ltr501_write_contr(data, data->als_contr,
 		data->ps_contr);
 }
-#endif
 
-static SIMPLE_DEV_PM_OPS(ltr501_pm_ops, ltr501_suspend, ltr501_resume);
+static DEFINE_SIMPLE_DEV_PM_OPS(ltr501_pm_ops, ltr501_suspend, ltr501_resume);
 
 static const struct acpi_device_id ltr_acpi_match[] = {
 	{ "LTER0501", ltr501 },
@@ -1661,7 +1659,7 @@ static struct i2c_driver ltr501_driver = {
 	.driver = {
 		.name   = LTR501_DRV_NAME,
 		.of_match_table = ltr501_of_match,
-		.pm	= &ltr501_pm_ops,
+		.pm	= pm_sleep_ptr(&ltr501_pm_ops),
 		.acpi_match_table = ACPI_PTR(ltr_acpi_match),
 	},
 	.probe  = ltr501_probe,