fix: Quick fix to let CRSF be used with MPM wireless trainer - limiations apply (#1724)

* Let's do some dirty hack with MPM RX

Resolves #1671

* Use the right function to sync and shutdown sync on external MPM as well

radio/src/pulses/pulses.cpp

@@ -649,15 +649,8 @@ bool setupPulsesExternalModule(uint8_t protocol)
 
 #if defined(MULTIMODULE)
     case PROTOCOL_CHANNELS_MULTIMODULE:
-    {
-      ModuleSyncStatus& status = getModuleSyncStatus(EXTERNAL_MODULE);
-      if (status.isValid())
-        mixerSchedulerSetPeriod(EXTERNAL_MODULE, status.getAdjustedRefreshRate());
-      else
-        mixerSchedulerSetPeriod(EXTERNAL_MODULE, MULTIMODULE_PERIOD);
       setupPulsesMultiExternalModule();
       return true;
-    }
 #endif
 
 #if defined(PPM)