iio: health/afe4404: mark suspend/resume functions __maybe_unused

The newly added afe4404 driver implements suspend/resume using the
SIMPLE_DEV_PM_OPS() macro, which leaves out references to the actual
functions when CONFIG_PM is disabled, causing a harmless warning:

health/afe4404.c:509:12: error: 'afe4404_suspend' defined but not used
health/afe4404.c:530:12: error: 'afe4404_resume' defined but not used

This marks the functions as __maybe_unused so we don't get those
warnings.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 87aec56e27ef ("iio: health: Add driver for the TI AFE4404 heart monitor")
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/health/afe4404.c

@@ -477,7 +477,7 @@ static const struct of_device_id afe4404_of_match[] = {
 MODULE_DEVICE_TABLE(of, afe4404_of_match);
 #endif
 
-static int afe4404_suspend(struct device *dev)
+static int __maybe_unused afe4404_suspend(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct afe4404_data *afe = iio_priv(indio_dev);
@@ -498,7 +498,7 @@ static int afe4404_suspend(struct device *dev)
 	return 0;
 }
 
-static int afe4404_resume(struct device *dev)
+static int __maybe_unused afe4404_resume(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct afe4404_data *afe = iio_priv(indio_dev);