rtc: Skip the suspend/resume handling if persistent clock exist

All the RTC suspend and resume functions are to compensate the
sleep time, but this is already done in timekeeping.c if persistent
clock exist.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Arve Hjønnevåg <arve@android.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

drivers/rtc/class.c

@@ -50,6 +50,10 @@ static int rtc_suspend(struct device *dev, pm_message_t mesg)
 	struct rtc_device	*rtc = to_rtc_device(dev);
 	struct rtc_time		tm;
 	struct timespec		delta, delta_delta;
+
+	if (has_persistent_clock())
+		return 0;
+
 	if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
 		return 0;
 
@@ -88,6 +92,9 @@ static int rtc_resume(struct device *dev)
 	struct timespec		new_system, new_rtc;
 	struct timespec		sleep_time;
 
+	if (has_persistent_clock())
+		return 0;
+
 	rtc_hctosys_ret = -ENODEV;
 	if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
 		return 0;