Horus power loop fixed if power button is held pressed.

radio/src/opentx.h

@@ -311,7 +311,7 @@
   #define cli()
   #define sei()
   extern void boardInit();
-  #if defined(PCBTARANIS)
+  #if defined(PCBTARANIS) or defined(PCBHORUS)
     extern void boardOff();
   #else
     #define boardOff()                 pwrOff();

radio/src/targets/horus/board_horus.cpp

@@ -167,7 +167,20 @@ void boardInit()
 
   ledBlue();
 }
-#endif
+
+void boardOff()
+{
+  BACKLIGHT_OFF();
+
+  while (pwrPressed()) {
+    wdt_reset();
+  }
+
+  SysTick->CTRL = 0; // turn off systick
+  pwrOff();
+}
+
+#endif // #if !defined(SIMU)
 
 #if defined(USB_JOYSTICK) && !defined(SIMU)
 extern USB_OTG_CORE_HANDLE USB_OTG_dev;