network layer (ether).
- Don't abuse module names to facilitate ifconfig module loading;
such abuse isn't really needed. (And if we do need type information
associated with a module then we should make it explicit and not
use hacks.)
- bus_space'ify
- generate fake ethernet address using read_random() instead of reading
from timer i/o ports
Other minor fixes:
- remove "hack" in connect_to_master()
- use M_ZERO
- remove unused variable in sbni_ioctl()
- properly release irq in sbni_attach_isa() on attach errors
