Move properties from virtio-*-pci to virtio-*-device.
Also make better use of QOM and attach common properties
to the abstract parent classes (virtio-input-device and
virtio-input-pci-device).

Switch the hid device instance init functions over to use
virtio_instance_init_common, so we get the properties of the
virtio device aliased properly to the virtio pci proxy.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>