device drivers:
- Various native device entries in cdevsw/bdevsw.
- Rework the interrupt infrastructure to provide more flexibility to
the platform-dependent back-end. Rewrite the "ofwgen" simulated
interrupt routines to reflect the changes.
- Clear out the BAT registers and set the fixed battable entries before
calling the platform init routine. The platform init routine is allowed
to set entries in the battable.
- Don't call the platform cons_init routine until after translation is
enabled -- we might need translation to work in order to access bus
space.
thorpej