fixup! fixup! fixup! fixup! cpu/stm32/periph/rtc: don't stop RTC for every lock

Author: crasbe

cpu/stm32/periph/rtc_all.c

@@ -305,9 +305,10 @@ void rtc_init(void)
         rtc_unlock();
         /* reset configuration */
         RTC->CR = 0;
-        RTC_REG_ISR = RTC_ISR_INIT;
+        rtc_enter_init_mode();
         /* configure prescaler (RTC PRER) */
         RTC->PRER = (PRE_SYNC | (PRE_ASYNC << 16));
+        rtc_exit_init_mode();
         rtc_lock();
     }