BTM_SetDiscoverability() function

* Function BTM_SetDiscoverability * Description This function is called to set the device into or out of * discoverable mode. Discoverable mode means inquiry * scans are enabled. If a value of '0' is entered for window or * interval, the default values are used. * Returns BTM_SUCCESS if successful * BTM_BUSY if a setting of the filter is already in progress * BTM_NO_RESOURCES if couldn't get a memory pool buffer * BTM_ILLEGAL_VALUE if a bad parameter was detected * BTM_WRONG_MODE if the device is not up.