As we might not always have a device id, it is impossible to always
match MEMORY_DEVICE_SIZE_CHANGE events to an actual device. Let's
include the qom-path in the event, which allows for reliable mapping of
events to devices.

Fixes: 722a3c78 ("virtio-pci: Send qapi events when the virtio-mem size changes")
Suggested-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20210929162445.64060-3-david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>