scsi target to a disk unit for setroot(). If anyone knows a better way
to do this, please let me know. The only other way I could think of
would be to add a field in disk.h:struct dkdevice to reference the scsi
target. Ideally, the correct boot device would be passed in from the
booter. As we only have one scsi bus (until we support NuBUS scsi
cards), it makes sense to be backward-compatible (especially since mac
weenies seem to need help tying their shoes).
modified to function with the mac code. It currently doesn't map
the configured devices, but it does force the boot disk to be sd0.
The user-level stuff has been #ifdef'ed for sanity.
