Merge pull request #632 from oltaco/dev

WioTrackerL1: add poweroff support

variants/wio-tracker-l1/WioTrackerL1Board.h

@@ -38,5 +38,9 @@ public:
     NVIC_SystemReset();
   }
 
+  void powerOff() override {
+    sd_power_system_off();
+  }
+
   bool startOTAUpdate(const char* id, char reply[]) override;
 };