In osiop_checkintr(), bail out early and do not claim the interrupt for ``can't happen'' situations (which happen sometimes on mvme88k), rather than inadvertently dereference NULL pointers and panic.
In osiop_checkintr(), bail out early and do not claim the interrupt for
``can't happen'' situations (which happen sometimes on mvme88k), rather
than inadvertently dereference NULL pointers and panic.

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