libbrillo: Set RollbackAllowedMilestones enterprise default to 0

Changing the default value of RollbackAllowedMilestones policy
from 4 to 0 for enterprises (already 0 for consumer devices).

Until the kernel and firmware key versions can be set properly
from Omaha, we don't freeze key rolls by default, only if it's
explicitly specified using enterprise policy.

BUG=chromium:847226
TEST='cros_run_unit_tests --board=caroline --packages libbrillo'

Change-Id: I4451a4e31f475a8b7557fea4f44dc35afe95ef0b
Reviewed-on: https://chromium-review.googlesource.com/1078811
Commit-Ready: Marton Hunyady <hunyadym@chromium.org>
Tested-by: Marton Hunyady <hunyadym@chromium.org>
Reviewed-by: Mattias Nissler <mnissler@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
3 files changed