snapshot 200811 amd64 fails to attach Parallels 4 uhci

[Nick Hibma]

> >>> ehci0: <Intel 82801FB (ICH6) USB 2.0 controller> mem
> >>> 0xe8000000-0xe80003ff
> >>> irq 19 at device 29.7 on pci0
> >>> ehci0: pre-2.0 USB rev
> >>> device_attach: ehci0 attach returned 6

Hardcode the revision to USB 2.0 and you should be ok.

I guess that Parallells does not set a value correctly (or indicates it is 
emulating). Perhaps you could add a printf to display it?

Nick