usb: xhci: Add support for URB_ZERO_PACKET to bulk/sg transfers

commit 4758dcd19a7d9ba9610b38fecb93f65f56f86346 upstream.

This commit checks for the URB_ZERO_PACKET flag and creates an extra
zero-length td if the urb transfer length is a multiple of the endpoint's
max packet length.

Change-Id: I8b0f27a2e6a242120f4d568c48c09f6c9889b9a1
Signed-off-by: Reyad Attiyat <reyad.attiyat@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>