iio: dac: ds4424: Switch to DEFINE_SIMPLE_DEV_PM_OPS() and pm_sleep_ptr()

Using these newer macros allows the compiler to remove the unused
structure and functions when !CONFIG_PM_SLEEP + removes the need to
mark pm functions __maybe_unused.

Signed-off-by: Jonathan Cameron <[e-mail]>
Cc: Ismail H. Kose <[e-mail]>
Reviewed-by: Paul Cercueil <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/iio/dac/ds4424.c

···
 	return ret;
 }
 
-static int __maybe_unused ds4424_suspend(struct device *dev)
+static int ds4424_suspend(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
···
 	return ret;
 }
 
-static int __maybe_unused ds4424_resume(struct device *dev)
+static int ds4424_resume(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
···
 	return ret;
 }
 
-static SIMPLE_DEV_PM_OPS(ds4424_pm_ops, ds4424_suspend, ds4424_resume);
+static DEFINE_SIMPLE_DEV_PM_OPS(ds4424_pm_ops, ds4424_suspend, ds4424_resume);
 
 static const struct iio_info ds4424_info = {
 	.read_raw = ds4424_read_raw,
···
 	.driver = {
 		.name	= "ds4424",
 		.of_match_table = ds4424_of_match,
-		.pm     = &ds4424_pm_ops,
+		.pm     = pm_sleep_ptr(&ds4424_pm_ops),
 	},
 	.probe		= ds4424_probe,
 	.remove		= ds4424_remove,