chromeos_config: mark wizpig, reef, reef-uni experimental

The tree status is intended to mark things as experimental for the short
term. These boards have been continuously experimental for over a week.
Moving the flag to config.

BUG=chromium:765686
TEST=None

Change-Id: I70a67b3885cf11a9443f5b808aa99dcd7a795e62
Reviewed-on: https://chromium-review.googlesource.com/742101
Commit-Ready: Aviv Keshet <akeshet@chromium.org>
Tested-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
2 files changed