Well, partly just papering over the issues. But without proper scsi bus
infrastructure we hardly can do better. Changes:
* Avoid auto-attach by setting the bus number to -1.
* Ignore the unit value calculated by drive_init().
* Explicitly attach the devices to the adapter.
* Add sanity checks. Don't allow attaching scsi drives to your
network device.
* Kill the bus+unit printing. The values are bogus, and we can't
easily figure the correct ones. I doubt this ever worked correctly
with multiple scsi adapters present in the system.
Should come more close to the expected behavior now ...
Oh, and pc-bios/bios.bin needs a update too, otherwise pci hotplug
doesn't work at all.