[moblab] Blacklist the new arc interface when booting moblab.

Moblab has a rather unusual networking setup and it does not have
arc installed, adding this parameter has stabalized some hard to
diagnose networking issues in test builds where the moblab would
fail to get an ip address after the shill was restarted.

The failure was hard to reproduce ( rebooting would often solve
the issue ) but in local testing the network has been much better
with this param added and it has no negative side effects.

BUG=None
TEST=local moblab build and test.

Change-Id: Ia3da2533b6f60809741c06ca36a37dc28664f6a9
Reviewed-on: https://chromium-review.googlesource.com/1540487
Commit-Ready: Keith Haddow <haddowk@chromium.org>
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Keith Haddow <haddowk@chromium.org>
Reviewed-by: Keith Haddow <haddowk@chromium.org>
Reviewed-by: Matt Mallett <mattmallett@chromium.org>
1 file changed