AP_IOMCU: Add #pragma once

Added #pragma once to AP_IOMCU as this caused compile issues when adding bindings to the LUA scripting

libraries/AP_IOMCU/AP_IOMCU.h

@@ -4,6 +4,7 @@
   For bootstrapping this will initially implement the px4io protocol,
   but will later move to an ArduPilot specific protocol
  */
+#pragma once
 
 #include <AP_HAL/AP_HAL.h>