[autotest] Fix afe_utils to maintain compatability with existing builds.

BUG=chromium:586327
TEST=run AU test

Change-Id: I5670055e44522ba269e9541014abe04bfc45ca16
Reviewed-on: https://chromium-review.googlesource.com/328180
Trybot-Ready: Dan Shi <dshi@google.com>
Tested-by: Dan Shi <dshi@google.com>
Reviewed-by: Kevin Cheng <kevcheng@chromium.org>
Commit-Queue: Dan Shi <dshi@google.com>
2 files changed