Add support for pseudo devices. Based on the new code in config.
Add support for pseudo devices. Based on the new code in config.

N.B. this change requires the kernel to be configured with a new
     config since it need new information from ioconf.c.

-moj ok @deraadt

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