stm32/powerctrl: Set H7 RTC wakeup flags.

ports/stm32/powerctrl.c

@@ -705,7 +705,8 @@ void powerctrl_enter_standby_mode(void) {
     // clear global wake-up flag
     PWR->CR2 |= PWR_CR2_CWUPF6 | PWR_CR2_CWUPF5 | PWR_CR2_CWUPF4 | PWR_CR2_CWUPF3 | PWR_CR2_CWUPF2 | PWR_CR2_CWUPF1;
     #elif defined(STM32H7)
-    // TODO
+    EXTI_D1->PR1 = 0x3fffff;
+    PWR->WKUPCR |= PWR_WAKEUP_FLAG1 | PWR_WAKEUP_FLAG2 | PWR_WAKEUP_FLAG3 | PWR_WAKEUP_FLAG4 | PWR_WAKEUP_FLAG5 | PWR_WAKEUP_FLAG6;
     #elif defined(STM32L4) || defined(STM32WB)
     // clear all wake-up flags
     PWR->SCR |= PWR_SCR_CWUF5 | PWR_SCR_CWUF4 | PWR_SCR_CWUF3 | PWR_SCR_CWUF2 | PWR_SCR_CWUF1;