ARC: Add partial support for Digilent HS-2 cable

Digilent HS-2 uses different chip in comparison to HS-1, FTDI 232H instead
of 2232C and it has different USB ProductID. This patch adds corresponding
PID to the ML-509 targets.

Signed-off-by: Anton Kolesov <akolesov@synopsys.com>
ARC: Refer to CPU by name instead of id

OpenOCD was printing warning that CPU should be referred by name instead of
number. This patch corrects it.

Signed-off-by: Anton Kolesov <akolesov@synopsys.com>
Merge pull request #10 from anthony-kolesov/add-digilenths2-partially

Add digilenths2 partially