iio: chemical: scd4x: 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: Roan van Dijk <[e-mail]>
Reviewed-by: Paul Cercueil <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/iio/chemical/scd4x.c

···
 	},
 };
 
-static int __maybe_unused scd4x_suspend(struct device *dev)
+static int scd4x_suspend(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct scd4x_state *state  = iio_priv(indio_dev);
···
 	return regulator_disable(state->vdd);
 }
 
-static int __maybe_unused scd4x_resume(struct device *dev)
+static int scd4x_resume(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct scd4x_state *state = iio_priv(indio_dev);
···
 	return scd4x_send_command(state, CMD_START_MEAS);
 }
 
-static __maybe_unused SIMPLE_DEV_PM_OPS(scd4x_pm_ops, scd4x_suspend, scd4x_resume);
+static DEFINE_SIMPLE_DEV_PM_OPS(scd4x_pm_ops, scd4x_suspend, scd4x_resume);
 
 static void scd4x_stop_meas(void *state)
 {
···
 	.driver = {
 		.name = KBUILD_MODNAME,
 		.of_match_table = scd4x_dt_ids,
-		.pm = &scd4x_pm_ops
+		.pm = pm_sleep_ptr(&scd4x_pm_ops),
 	},
 	.probe = scd4x_probe,
 };