Flysky Hall Stick MOD using UART4 by disabling stick A/D, resolving #140. (#149)

* Flysky Hall Stick MOD using UART4 by disabling stick A/D.

* Fixed build error.

* Added Flysky hall stick mod in test targets.

* Changed ADC disable for Flysky hall sticks method.

radio/src/targets/common/arm/stm32/timers_driver.cpp

@@ -20,6 +20,8 @@
 
 #include "opentx.h"
 
+extern void flysky_hall_stick_loop( void );
+
 // Start TIMER at 2000000Hz
 void init2MhzTimer()
 {
@@ -62,6 +64,10 @@ void interrupt5ms()
   DEBUG_TIMER_STOP(debugTimerHaptic);
 #endif
 
+#if defined(FLYSKY_HALL_STICKS)
+  flysky_hall_stick_loop();  // TODO: need to put in 1ms timer loop for best performance
+#endif
+
   if (pre_scale == 2) {
     pre_scale = 0;
     DEBUG_TIMER_START(debugTimerPer10ms);