fetch_device
bt_usb_dev* bdev = fetch_device((bt_usb_dev*)cookie, 0);
bdev = fetch_device(NULL, hid);
bt_usb_dev* fetch_device(bt_usb_dev* dev, hci_id hid);
bt_usb_dev* bdev = fetch_device(NULL, hid);
bt_usb_dev* bdev = fetch_device(NULL, hid);
#define GET_DEVICE(nbuf) fetch_device(NULL, (nbuf->DEVICEFIELD&0xFF))