futility: remove obsolete dev_sign_file command

This wasn't being used anywhere, so out it goes.

BUG=chromium:231457
BRANCH=none
TEST=make runtests

Change-Id: If3865f54ac29655ee7d520f00e618f490f25c619
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/235481
Reviewed-by: Randall Spangler <rspangler@chromium.org>
4 files changed