BUG：A problem about registration update that can cause a memory leak.

[xiaoshan1234]

Detail

When the client registration update message receives no reply, the callback function cannot fully release the allocated memory。
I made some modifications to fix this issue, and it truly worked in my business. I hope more people can test my changes to see if they introduce any new problems

Original Code

static void prv_handleRegistrationUpdateReply(lwm2m_context_t * contextP,
                                              lwm2m_transaction_t * transacP,
                                              void * message)
{
    coap_packet_t * packet = (coap_packet_t *)message;
    registration_data_t * dataP = (registration_data_t *)(transacP->userData);

   // ......
    
    if (packet != NULL && packet->code != COAP_231_CONTINUE)
    {
        lwm2m_free(dataP->payload);
        transaction_free_userData(contextP, transacP);
    }
}

My Code

static void prv_handleRegistrationUpdateReply(lwm2m_context_t * contextP,
                                              lwm2m_transaction_t * transacP,
                                              void * message)
{
    coap_packet_t * packet = (coap_packet_t *)message;
    registration_data_t * dataP = (registration_data_t *)(transacP->userData);

   // ......
    
    if (packet != NULL && packet->code == COAP_231_CONTINUE)
    {
        ; // pass 
    }
    else
    {
        uint8_t * payload = dataP->payload;
        if (transaction_free_userData(contextP, transacP))
        {
            lwm2m_free(payload);
        }
    }

}

[LukasWoodtli]

Thank you for your contribution. Would you consider making a proper PR with your changes? That would be awesome!