Add AUX2 (#7588)

AUX2 added

radio/src/opentx.cpp

@@ -1939,6 +1939,10 @@ void opentxInit()
   auxSerialInit(g_eeGeneral.auxSerialMode, modelTelemetryProtocol());
 #endif
 
+#if defined(AUX2_SERIAL)
+  aux2SerialInit(g_eeGeneral.aux2SerialMode, modelTelemetryProtocol());
+#endif
+
 #if MENUS_LOCK == 1
   getMovedSwitch();
   if (TRIMS_PRESSED() && g_eeGeneral.switchUnlockStates==switches_states) {