rtc: meson: mark PM functions as __maybe_unused

The meson_vrtc_set_wakeup_time() function is only used by
the PM functions and causes a warning when they are disabled:

drivers/rtc/rtc-meson-vrtc.c:32:13: error: unused function 'meson_vrtc_set_wakeup_time' [-Werror,-Wunused-function]

Remove the #ifdef around the callers and add a __maybe_unused
annotation as a more reliable way to avoid these warnings.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20190906152438.1533833-1-arnd@arndb.deSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-meson-vrtc.c

@@ -91,8 +91,7 @@ static int meson_vrtc_probe(struct platform_device *pdev)
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
-static int meson_vrtc_suspend(struct device *dev)
+static int __maybe_unused meson_vrtc_suspend(struct device *dev)
 {
 	struct meson_vrtc_data *vrtc = dev_get_drvdata(dev);
 
@@ -121,7 +120,7 @@ static int meson_vrtc_suspend(struct device *dev)
 	return 0;
 }
 
-static int meson_vrtc_resume(struct device *dev)
+static int __maybe_unused meson_vrtc_resume(struct device *dev)
 {
 	struct meson_vrtc_data *vrtc = dev_get_drvdata(dev);
 
@@ -131,7 +130,7 @@ static int meson_vrtc_resume(struct device *dev)
 	meson_vrtc_set_wakeup_time(vrtc, 0);
 	return 0;
 }
-#endif
+
 static SIMPLE_DEV_PM_OPS(meson_vrtc_pm_ops,
 			 meson_vrtc_suspend, meson_vrtc_resume);