containers: fix three cases' exit status

In iproute2 whose version is earlier than v3.0.0, ip
command doesn't support netns object. In this condition,
running three cases (netns_devices.sh, netns_devices2.sh
and netns_isolation.sh) will exit with TFAIL. It is not
suitable, so fix these cases' exit status with TCONF.

Signed-off-by: Xing Gu <gux.fnst@cn.fujitsu.com>
4 files changed