PPC: mac99: Always add USB controller

The mac99 machines always have a USB controller. Usually not having one around
doesn't hurt quite as much, but Mac OS 9 really really wants one or it crashes
on bootup.

So always add OHCI to make it happy.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
