COM0 and COM1 LED handler may block IO process (LFW)

In the LFW use case, the AP task uses uses the LED script feature from rcX to handle the COM0 and COM1 LEDs. The handler process consumes 70us and is triggered every 200ms within a high prior context (RX_TIMER).

The RX_TIMER context has to be set to a lower priority than the IO handler (AP task)