libpayload: Fill gaps in the xHCI driver

Well, it turned out to be more as some gaps ;)
but we finally have xHCI running. It's well tested against a QM77 Ivy
Bridge board.

We have no SuperSpeed support (yet). On Ivy Bridge, SuperSpeed is not
advertised and USB 3 devices will just work at HighSpeed.

There are still some bit fields in xhci_private.h, so this might need
little more work to run on ARM.

Change-Id: I7a2cb3f226d24573659142565db38b13acdc218c
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Signed-off-by: Patrick Georgi <patrick.georgi@secunet.com>
Reviewed-on: http://review.coreboot.org/3452
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
9 files changed