Corrected field length of return_code
Corrected field length of return_code

njh/mqtt-sn-tools,MichalFoksa/mqtt-sn-tools,adamrenner/mqtt-sn-tools-contiki,adamrenner/mqtt-sn-tools-contiki,MichalFoksa/mqtt-sn-tools,adamrenner/mqtt-sn-tools-contiki,njh/mqtt-sn-tools