rtc: cmos: avoid unused function warning

A bug fix for the ACPI side of this driver caused a harmless
build warning:

drivers/rtc/rtc-cmos.c:1115:13: error: 'cmos_check_acpi_rtc_status' defined but not used [-Werror=unused-function]
static void cmos_check_acpi_rtc_status(struct device *dev,

We can avoid the warning and simplify the driver at the same time
by removing the #ifdef for CONFIG_PM and rely on the SIMPLE_DEV_PM_OPS()
to set everything up correctly. cmos_resume() has to get marked
as __maybe_unused so we don't introduce another warning, and
the two variants of cmos_poweroff() can get merged into one using
an IS_ENABLED() check.

Fixes: 983bf1256edb ("rtc: cmos: Clear ACPI-driven alarms upon resume")
Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Alexandre Belloni <[e-mail]>

drivers/rtc/rtc-cmos.c

···
 	return retval;
 }
 
-#ifdef CONFIG_PM
-
 static int cmos_suspend(struct device *dev)
 {
 	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
···
  */
 static inline int cmos_poweroff(struct device *dev)
 {
+	if (!IS_ENABLED(CONFIG_PM))
+		return -ENOSYS;
+
 	return cmos_suspend(dev);
 }
-
-#ifdef	CONFIG_PM_SLEEP
 
 static void cmos_check_wkalrm(struct device *dev)
 {
···
 static void cmos_check_acpi_rtc_status(struct device *dev,
 				       unsigned char *rtc_control);
 
-static int cmos_resume(struct device *dev)
+static int __maybe_unused cmos_resume(struct device *dev)
 {
 	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
 	unsigned char tmp;
···
 
 	return 0;
 }
-
-#endif
-#else
-
-static inline int cmos_poweroff(struct device *dev)
-{
-	return -ENOSYS;
-}
-
-#endif
 
 static SIMPLE_DEV_PM_OPS(cmos_pm_ops, cmos_suspend, cmos_resume);
 
···
 	.shutdown	= cmos_platform_shutdown,
 	.driver = {
 		.name		= driver_name,
-#ifdef CONFIG_PM
 		.pm		= &cmos_pm_ops,
-#endif
 		.of_match_table = of_match_ptr(of_cmos_match),
 	}
 };