Merge remote-tracking branch 'kraxel/usb.76' into staging

* kraxel/usb.76:
  usb-host: Initialize dev->port the obviously safe way
  usb-host: Drop superfluous null test from usb_host_auto_scan()
  ehci: Assert state machine is sane w.r.t. EHCIQueue
  xhci: nuke transfe5rs on detach
  xhci: call xhci_detach_slot on root port detach too
  xhci: create xhci_detach_slot helper function

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>