With the previous changes, we can now let the ICS_KVM class inherit
directly from ICS_BASE class and not from the intermediate ICS_SIMPLE.
It makes the class hierarchy much cleaner.
What is left in the top classes is the low level interface to access
the KVM XICS device in ICS_KVM and the XICS emulating handlers in
ICS_SIMPLE.
This should not break migration compatibility.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>