xics: drop ICPStateClass::cpu_setup() handler

xics: drop ICPStateClass::cpu_setup() handler

The cpu_setup() handler is only implemented by xics_kvm, where it really
does a typical "realize" job. Moreover, the realize() handler is called
shortly after cpu_setup(), on the same path.

This patch converts xics_kvm to implement realize() instead of cpu_setup().

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