RTC: Re-enable UIE timer/polling emulation

This patch re-enables UIE timer/polling emulation for rtc devices
that do not support alarm irqs.

CC: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
CC: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index 80408e7..89c3e51 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -250,6 +250,7 @@
 extern int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc,
 						unsigned int enabled);
 
+void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode);
 void rtc_aie_update_irq(void *private);
 void rtc_uie_update_irq(void *private);
 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer);