boards/native: call rtc_init from board_init

boards/native/board_init.c

@@ -15,6 +15,7 @@
  */
 #include <stdio.h>
 #include "board.h"
+#include "periph/rtc.h"
 
 #include "board_internal.h"
 
@@ -30,6 +31,9 @@ void board_init(void)
 {
     LED0_OFF;
     LED1_ON;
+#ifdef MODULE_PERIPH_RTC
+    rtc_init();
+#endif
     puts("RIOT native board initialized.");
 }