build system: add manual board id support

This patch adds manual board id support to coreboot and
selects manual board ids vs automatic (ie strap based)
where appropriate in the mainboards.

CQ-DEPEND=CL:262935
BRANCH=none
BUG=chrome-os-partner:37593
TEST=emerge-urara coreboot, see no board_id file
     emerge-buranku coreboot, see board_id file

Change-Id: Ia04e5498a01f35c5418698ecaf3197f56415e789
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 3bdb1fa092005be24de9fc68998053982648da85
Original-Change-Id: I4f0820233a485bf92598a739b81be2076d4e6ae7
Original-Signed-off-by: Stefan Reinauer <reinauer@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/262745
Original-Reviewed-by: Vadim Bendebury <vbendeb@google.com>
Reviewed-on: http://review.coreboot.org/9905
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
3 files changed