ems_usb: Added support for EMS CPC-USB/ARM7 CAN/USB interface

This patch adds support for one channel CAN/USB interace CPC-USB/ARM7 from
EMS Dr. Thomas Wuensche (http://www.ems-wuensche.com

).

Signed-off-by: Sebastian Haas <haas@ems-wuensche.com>
Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: David S. Miller <davem@davemloft.net>