USB: Add stream ID field to struct urb.

Bulk endpoint streams were added in the USB 3.0 specification.  Streams
allow a device driver to overload a bulk endpoint so that multiple
transfers can be queued at once.

Add a new field, stream_id, to struct urb so that USB 3.0 drivers can
specify which stream they want the URB to be queued to.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>