interface/ftdi/olimex-arm-usb-ocd-h: fix nTRST control definition

According to my inspection of an Olimex ARM-USB-OCD-H adapter ACBUS0
is connected directly to an SN74LVC2T45 buffer input B2, and the
corresponding output A2 is connected directly to the JTAG
connector. It seems the information in the Olimex flyer is incorrect
for the -H version and TRST can't be tri-stated, ACBUS2 is unused.

The older ARM-USB-OCD device has SN74AC244 for an output buffer and
ACBUS2 controls its !2OE, ACBUS0 connected to 2A1 (2Y1 is nTRST), in
accordance with the information flyer.

Change-Id: I22828b7b959b6f62c3f51367feb8fab9705641e5
Reported-by: Tim Sander <tim@krieglstein.org>
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Reviewed-on: http://openocd.zylin.com/2286
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-by: Tim Sander <tim@krieglstein.org>