common.sh: delete unused ALL_BOARDS

This hasn't been used since CL:17868.  Drop it here.

BUG=None
TEST=CQ passes

Change-Id: I212d2579fa78ce42ae0283ee1834a06b0ddbba69
Reviewed-on: https://chromium-review.googlesource.com/1764949
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Alex Klein <saklein@chromium.org>
1 file changed