jlink: Add on-board nRF51-DK USB VID and PID

jlink: Add on-board nRF51-DK USB VID and PID

* Add USB VID and PID for the J-Link interface running on the Nordic
  Semiconductor nRF51-DK.  Also tested with debug out port to debug
  external boards.
* Elimiantes need for `-c "jlink pid 0x1015"` on the openocd cmd line.

Change-Id: Ib23acb72b9f5183b76fc7dc22b556982869ae830
Signed-off-by: Kyle Manna <kyle@kylemanna.com>
Reviewed-on: http://openocd.zylin.com/2775
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>