Applied the usb_xhci part of the USB patch by Ben Lunt.
Notes by Ben:
This emulates a NEC/Renesas uPD720202 2-port (2 socket, 4-port register sets)
Root Hub xHCI Host Controller.
Many, many thanks to Renesas for their work and effort in helping my research.

I have tested in with my own tests and WinXP Home Edition SP3.

Use port1 and port2 to emulate a Super-speed device, and use port3 and port4
to emulate Low-, Full-, or High-speed devices.

NOTE: The Windows driver for this device uses a proprietary detection
mechanism and we don't have the permission to implement it. That's why it only
works fine with non-Windows guests.


git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@12493 6c8e4198-a580-4521-a02f-c9ae86df1db9