motd: MFC: unbreak for source upgrade

In case of source upgrade path from 12.x proper merge of new /etc
installs /etc/motd.template. Becase of that, the system is left
without symlink /etc/motd -> /var/run/motd but with stale /etc/motd contents.

Fix it creating symlink despite of presence of /etc/motd.template.

(cherry picked from commit 79a96e294c1acb4a2d17447a35f08647a6d09978)