usb: wusbcore: fix endianess issues when using dwTransferID

Add a new function to get the xfer ID in little endian format
(wa_xfer_id_le32), and use it instead of wa_xfer_id where appropriate.

Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>