adding R_RTC_ClockSourceSet when setting rtc time FIXME

it may be required to run it also when the device is powered down, but
vrtc is not being powered

Author: andreagilardoni

libraries/RTC/src/RTC.cpp

@@ -551,6 +551,8 @@ bool openRtc() {
 }
 
 bool setRtcTime(rtc_time_t time) {
+    R_RTC_ClockSourceSet(&rtc_ctrl);
+
     if(FSP_SUCCESS == R_RTC_CalendarTimeSet(&rtc_ctrl, &time) ) {
         return true;
     }