Make pci_intr_map(9) fail if the interrupt line register is set to 0xff. Prevents crashes later on when we try to estabish the interrupt.
Make pci_intr_map(9) fail if the interrupt line register is set to 0xff.
Prevents crashes later on when we try to estabish the interrupt.

ok miod@, deraadt@

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