BTM_SecGetDeviceLinkKey() function

* Function BTM_SecGetDeviceLinkKey * Description This function is called to obtain link key for the device * it returns BTM_SUCCESS if link key is available, or * BTM_UNKNOWN_ADDR if Security Manager does not know about * the device or device record does not contain link key info * Parameters: bd_addr - Address of the device * link_key - Link Key is copied into this array