iio:proximity:as3935: 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.
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
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/20220130193147.279148-34-jic23@kernel.org

drivers/iio/proximity/as3935.c

@@ -296,7 +296,6 @@ static void calibrate_as3935(struct as3935_state *st)
 	as3935_write(st, AS3935_NFLWDTH, st->nflwdth_reg);
 }
 
-#ifdef CONFIG_PM_SLEEP
 static int as3935_suspend(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
@@ -338,12 +337,7 @@ static int as3935_resume(struct device *dev)
 	return ret;
 }
 
-static SIMPLE_DEV_PM_OPS(as3935_pm_ops, as3935_suspend, as3935_resume);
-#define AS3935_PM_OPS (&as3935_pm_ops)
-
-#else
-#define AS3935_PM_OPS NULL
-#endif
+static DEFINE_SIMPLE_DEV_PM_OPS(as3935_pm_ops, as3935_suspend, as3935_resume);
 
 static int as3935_probe(struct spi_device *spi)
 {
@@ -464,7 +458,7 @@ static struct spi_driver as3935_driver = {
 	.driver = {
 		.name	= "as3935",
 		.of_match_table = as3935_of_match,
-		.pm	= AS3935_PM_OPS,
+		.pm	= pm_sleep_ptr(&as3935_pm_ops),
 	},
 	.probe		= as3935_probe,
 	.id_table	= as3935_id,