protocols:fix null pointer dereference in write function
protocols:fix null pointer dereference in write function

limemicro/lms7suite,limemicro/lms7suite,myriadrf/LimeSuite,myriadrf/LimeSuite,limemicro/lms7suite,limemicro/lms7suite,myriadrf/LimeSuite,myriadrf/LimeSuite,myriadrf/LimeSuite,limemicro/lms7suite