(scan_or_find_devices): Add new args to return endpoint info and
interface number.
(ccid_open_reader, ccid_shutdown_reader): Take care of these new
args.
(bulk_in, bulk_out): Use the correct endpoints.
(ccid_transceive_apdu_level): New.
(ccid_transceive): Divert to above.
(parse_ccid_descriptor): Allow APDU level exchange mode.