image_signing: ensure_no_nonrelease_files.sh: convert to info/error helpers

This makes the output easier to follow when multiple scripts are being run.

BRANCH=None
BUG=chromium:714598
TEST=signing images still works

Change-Id: I666d3f5beee4b4e3e9903d546ef66917990a659e
Reviewed-on: https://chromium-review.googlesource.com/498231
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: David Riley <davidriley@chromium.org>
1 file changed