[Qemu-ppc] device crash test -- isa-fdc on ppc64/powernv

[John Snow]

Hi Thomas, I'm not particularly familiar with the various PPC flavors,
so please forgive me:

Apparently isa-fdc fails to instantiate on powernv (which appears to
have an ISA bus) because through one way or another, we never call:

isa_bus_dma, invoked by
DMA_init, invoked by, seemingly usually,
- i82374_realize in hw/dma/i82374.c

by comparison, the prep board appears to use the i82378 which in turn
uses the 82374 which is how we get our ISA DMA initialization.

pnv doesn't seem to have a DMA device on its ISA bus.

Should the powernv board be initializing something like this, or is it
more correct to just disable the isa-fdc device for this board for now
and be done with it?

--js