host-device: Bring interfaces down before moving.
host-device: Bring interfaces down before moving.

When trying to move a master and slave interface into a container it is not
possible without first bringing the interfaces down. This change ensures
that the interface is set to down prior to trying to move the interface
into the container. This matches the behaviour on moving an interface out
of the container.

Signed-off-by: cns <2e8e55a9d9efaf0f3ec132ed63f82561eedf3346@metaswitch.com>

containernetworking/plugins,containernetworking/plugins