by the isa.c bus driver and the "address/whatever not specified"
argument passed to leaf device drivers.
The former is "ISACF_XXX_DEFAULT" as generaterd by config(8), the latter
"ISA_UNKNOWN_XXX", defined in isavar.h.
This way we save a dependency of every ISA device driver on "locators.h".
with ACPI and PNPBIOS attachments; move it to new atppc_isadma.[ch]
and g/c previous atppc_isa_subr.[ch]
move attppc_isa_softc struct definition to atppc_isa.c, and reorganize
the attachment somewhat for better readability; also g/c detach support code
thorpej