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".
configuration of devices logically attached to the ISA bus:
* Change the isa_attach_args to have arrays of io, mem, irq, drq
resources.
* Add a "pnpnames" and a linked list of "pnpcompatnames" to the
isa_attach_args. If either of these members are non-NULL,
direct configuration of the bus is being performed. Add an
ISA_DIRECT_CONFIG() macro to test for this.
* Drivers are not allowed to modify the isa_attach_args unless
direct configuration is not being performed and the probe fucntion
is returning success.
* Adapt device drivers -- currently, all driver probe routines return
"no match" if ISA_DIRECT_CONFIG() evaluates to true.
