Section 3.2.9 in the XHCI specification about control transfers says
that we should use a normal-TRB if there are more TRBs extending the
data-stage TRB. Add a dedicated state bit to the internal USB transfer
flags to handle this case.

Reported by: Kohji Okuno <okuno.kohji@jp.panasonic.com>
MFC after: 1 week