iio:common:ssp: 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. Also switch to SIMPLE_DEV_PM_OPS
rather than open coding the structure.

Removing instances of this approach from IIO also stops them being
copied into new drivers.

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

drivers/iio/common/ssp_sensors/ssp_dev.c

···
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
 static int ssp_suspend(struct device *dev)
 {
 	int ret;
···
 
 	return 0;
 }
-#endif /* CONFIG_PM_SLEEP */
 
-static const struct dev_pm_ops ssp_pm_ops = {
-	SET_SYSTEM_SLEEP_PM_OPS(ssp_suspend, ssp_resume)
-};
+static DEFINE_SIMPLE_DEV_PM_OPS(ssp_pm_ops, ssp_suspend, ssp_resume);
 
 static struct spi_driver ssp_driver = {
 	.probe = ssp_probe,
 	.remove = ssp_remove,
 	.driver = {
-		.pm = &ssp_pm_ops,
+		.pm = pm_sleep_ptr(&ssp_pm_ops),
 		.of_match_table = ssp_of_match,
 		.name = "sensorhub"
 	},