RTWN_BULK_TX_BK
rtwn_config[RTWN_BULK_TX_BK].endpoint = addr[2];
rtwn_config[RTWN_BULK_TX_BK].endpoint = addr[1];
rtwn_config[RTWN_BULK_TX_BK].endpoint = addr[0];
[RTWN_BULK_TX_BK] = {
rtwn_bulk_tx_callback_qid(xfer, error, RTWN_BULK_TX_BK);