autotest: Move dbus2primitive to dbus_util.py

We'd like to use this in other tests, and it is inconvenient to reach in
WiFi code to do this.

BUG=chromium:418738
TEST=Calling `/usr/local/autotest/cros/scripts/profile list` still works.
network_WiFi_SimpleConnect.wifi_checkWPA_TKIP passes.

Change-Id: I3175dad5818fca572dfccaa899a36978f1757347
Reviewed-on: https://chromium-review.googlesource.com/223094
Tested-by: Christopher Wiley <wiley@chromium.org>
Reviewed-by: Thieu Le <thieule@chromium.org>
Commit-Queue: Christopher Wiley <wiley@chromium.org>
2 files changed