rtc: ds1511: remove unused function

Fix the following clang warning:

drivers/rtc/rtc-ds1511.c:108:1: warning: unused function
'rtc_write_alarm' [-Wunused-function].
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/1618475821-102974-1-git-send-email-jiapeng.chong@linux.alibaba.com

drivers/rtc/rtc-ds1511.c

@@ -104,12 +104,6 @@ rtc_write(uint8_t val, uint32_t reg)
 	writeb(val, ds1511_base + (reg * reg_spacing));
 }
 
-static inline void
-rtc_write_alarm(uint8_t val, enum ds1511reg reg)
-{
-	rtc_write((val | 0x80), reg);
-}
-
 static noinline uint8_t
 rtc_read(enum ds1511reg reg)
 {