flimflam_test: Add netmask when configuring backchannel ethernet.

Specifying a netmask allows the kernel to add the correct network route
to the backchannel ethernet interface.

TEST=Setup backchannel and verify the netmask is the same as eth0

Change-Id: I20538c05720bfbc440670fdd560638ccf0c19a6e
Reviewed-on: https://gerrit.chromium.org/gerrit/38150
Commit-Ready: Thieu Le <thieule@chromium.org>
Reviewed-by: Thieu Le <thieule@chromium.org>
Tested-by: Thieu Le <thieule@chromium.org>
1 file changed