A XICSFabric QOM interface is used by the XICS layer to manipulate the
ICP and ICS objects. Let's define the associated handlers for the
PowerNV machine. All handlers should be defined even if there is no
ICS under the PowerNV machine yet.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>