target-i386: cpu: Do not ignore error and fix apic parent

target-i386: cpu: Do not ignore error and fix apic parent

object_property_add_child() silently fails with error that it can't
create duplicate propery 'apic' as we already have 'apic' property
registered for 'apic' feature. As result generic device_realize puts
apic into unattached container.

As it's programming error, abort if name collision happens in future
and fix property name for apic_state to 'lapic', this way apic is
a child of cpu instance.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>