Drop num_ports argument for usb_ohci_init_pci(), everybody
calls it with num_ports == 3, so it is pointless.

Convert ohci pci device into qdev.
TODO: convert non-pci ohci adapters.

You can add a OHCI USB Controller to your virtual pc now using
'-device pci-ohci'.  Specifying a id is a good idea, so you can
attach usb devices to it, like this:

  -device pci-ohci,id=ohci
  -device usb-mouse,bus=ohci.0
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>