spapr: Abort if XICS interrupt controller cannot be initialized

spapr: Abort if XICS interrupt controller cannot be initialized

Failing to set any of the ICS property should really never happen:
- object_property_add_child() always succeed unless the child object
  already has a parent, which isn't the case here obviously since the
  ICS has just been created with object_new()
- the ICS has an "nr-irqs" property than can be set as long as the ICS
  isn't realized

In both cases, an error indicates there is a bug in QEMU. Propagating the
error, ie. exiting QEMU since spapr_irq_init() is called with &error_fatal
doesn't make much sense. Abort instead. This is consistent with what is
done with XIVE : both qdev_create() and qdev_prop_set_uint32() abort QEMU
on error.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <157403285265.409804.8683093665795248192.stgit@bahia.lan>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>