Fix lxc rootfs attached two devices in some action

During resizing/rebooting a lxc container, create_domain action
will be called and lxc rootfs will be attached to device again.
So before this action, We need to teardown the container to
make sure lxc_root_device is detached when container is destroyed.

Closes-bug: #1243083
Related-bug: #1208387

Change-Id: Idd1862c7f212dc253b6273b07b020c86a94e658e
Merge "Fix lxc rootfs attached two devices in some action"