rtc: interface: Remove unused return value from rtc_timer_cancel()

The rtc_timer_cancel() always returns 0 and cannot fail (calls only
other void-returning functions).

Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index b0709f8..587017e 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -200,7 +200,7 @@
 void rtc_timer_init(struct rtc_timer *timer, void (*f)(void *p), void *data);
 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
 		    ktime_t expires, ktime_t period);
-int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer);
+void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer);
 void rtc_timer_do_work(struct work_struct *work);
 
 static inline bool is_leap_year(unsigned int year)