[AR9X/9XPRO] Fix multi module not selectable for not Frsky radios (fix #4607)

companion/src/firmwares/opentx/opentxinterface.cpp

@@ -860,6 +860,8 @@ int OpenTxFirmware::isAvailable(PulsesProtocol proto, int port)
           case PULSES_DSM2:
           case PULSES_DSMX:
             return 1;
+          case PULSES_MULTIMODULE:
+            return id.contains("multimodule") ? 1 : 0;
           default:
             return 0;
         }