rtw_txring_next
if (ts->ts_first == rtw_txring_next(&sc->sc_regs, tdb))
rtw_txring_next(&sc->sc_regs, tdb));
next = rtw_txring_next(&sc->sc_regs, tdb);
next = rtw_txring_next(regs, tdb);
static u_int rtw_txring_next(struct rtw_regs *, struct rtw_txdesc_blk *);