cpu: Call cpu_synchronize_post_init() from DeviceClass::realize()

If hotplugged, synchronize CPU state to KVM.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
cpu: Introduce cpu_resume(), for single CPU

Also add a stub for it, to make possible to use it in qom/cpu.c,
which is shared with user emulators.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
cpu: Resume CPU from DeviceClass::realize() if hot-plugged

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>