iio:pressure:mpl3115: 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/20220130193147.279148-33-jic23@kernel.org

drivers/iio/pressure/mpl3115.c

@@ -301,7 +301,6 @@ static int mpl3115_remove(struct i2c_client *client)
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
 static int mpl3115_suspend(struct device *dev)
 {
 	return mpl3115_standby(iio_priv(i2c_get_clientdata(
@@ -317,11 +316,8 @@ static int mpl3115_resume(struct device *dev)
 		data->ctrl_reg1);
 }
 
-static SIMPLE_DEV_PM_OPS(mpl3115_pm_ops, mpl3115_suspend, mpl3115_resume);
-#define MPL3115_PM_OPS (&mpl3115_pm_ops)
-#else
-#define MPL3115_PM_OPS NULL
-#endif
+static DEFINE_SIMPLE_DEV_PM_OPS(mpl3115_pm_ops, mpl3115_suspend,
+				mpl3115_resume);
 
 static const struct i2c_device_id mpl3115_id[] = {
 	{ "mpl3115", 0 },
@@ -339,7 +335,7 @@ static struct i2c_driver mpl3115_driver = {
 	.driver = {
 		.name	= "mpl3115",
 		.of_match_table = mpl3115_of_match,
-		.pm	= MPL3115_PM_OPS,
+		.pm	= pm_sleep_ptr(&mpl3115_pm_ops),
 	},
 	.probe = mpl3115_probe,
 	.remove = mpl3115_remove,