dopoll
nvme_issue_shutdown(nvme_softc_t *sc, int dopoll)
if (dopoll == 0)
int nvme_issue_shutdown(nvme_softc_t *sc, int dopoll);
static int dopoll(int nfds, struct pollfd *fds, struct timespec *ts,
error = dopoll(uap->nfds, uap->fds, tsp, &sysmsg->sysmsg_result, 0);
error = dopoll(uap->nfds, uap->fds, ktsp, &sysmsg->sysmsg_result,