Silence most compiler warnings from m2mnsdlinterface.cpp
Silence most compiler warnings from m2mnsdlinterface.cpp

The GCC 5.x complained for invalid format specifiers for [u]int32_t
parameters. Fix these by using the proper PRI*32 macro. Fix also
the warnings for unused variables.

ARMmbed/mbed-client,ARMmbed/mbed-client,ARMmbed/mbed-client,tridonic-com/mbed-client,tridonic-com/mbed-client,tridonic-com/mbed-client