make sure only one set of xfers are set up for any number of opens of the tty/cua device.
make sure only one set of xfers are set up for any number of opens of the
tty/cua device.

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars