qdev: drop iobase properties from isa bus

qdev: drop iobase properties from isa bus

Lot of ISA devices work at fixed addresses, so having iobase
as bus property doesn't make much sense.  Devices which can
have different iobases will get a device property.

Also simply hard-code stuff which can't be configured anyway.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>