CC3200 Sl_start 是否是阻塞式的

sl_Start是用来打开NWP的，若没有回调函数它应该是阻塞的
若有InitCallBack，它将立即返回

Sl_Start – This function initializes the communication interface, sets the enable pin of the device, and calls
to the init complete callback. If no callback function is provided, the function is blocking until the device
finishes the initialization process.

\brief Start the SimpleLink device

This function initialize the communication interface, set the enable pin
of the device, and call to the init complete callback.
_i16 sl_Start(const void* pIfHdl, _i8* pDevName, const P_INIT_CALLBACK pInitCallBack);