- split softc size and match/attach out from cfdriver into
a new struct cfattach.
- new "attach" directive for files.*. May specify the name of
the cfattach structure, so that devices may be easily attached
to parents with different autoconfiguration semantics.
Does DMA with interrupts. Much faster than our old
driver which did only PIO transfers. (Thanks David!)
Could be used on the amiga, and probably others...