Only compile vio.c on iSeries and pSeries, since other PPC64 platforms
(PowerMac) don't use virtual IO.  The resulting #ifdefs in dma.c are kind
of ugly, but at least contained, and I can't see a nicer way of doing it
for the time being.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>