scratch. This driver adds support for USB3.0 devices. The XHCI
interface is also backwards compatible to USB2.0 and USB1.0 and will
evntually replace the OHCI/UHCI and EHCI drivers.
There will be follow-up commits during the coming week to link the
driver into the default kernel build and add missing USB3.0
functionality in the USB core. Currently only the driver files are
committed.
Approved by: thompsa (mentor)
