gooftool: add data_release_board as the board name of shipping image (from ToT to R12)

"release board" is something we may want to check in HWID validation process.

BUG=chrome-os-partner:5325,chrome-os-partner:5206
TEST=./gft_hwcompo.py # seeing x86-zgb-signed-mp-v2keys

Change-Id: I093a438cefb1cc20a5a6feb7e07be2f6f00e564b
Reviewed-on: http://gerrit.chromium.org/gerrit/5651
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Jay Kim <yongjaek@chromium.org>
2 files changed