[packet.unmarshal] Fix packet unmarshalling issues. Use of MType to distinguish packet type
[packet.unmarshal] Fix packet unmarshalling issues. Use of MType to distinguish packet type

LoRaWanSoFa/ttn,mgranberry/ttn,mgranberry/ttn,TheThingsNetwork/ttn,mgranberry/ttn,jvanmalder/ttn,LoRaWanSoFa/ttn,TheThingsNetwork/ttn,TheThingsNetwork/ttn,jvanmalder/ttn,jvanmalder/ttn