[ofono][dundee] At startup order dundee after dbus instead of syslog.

According to systemd documentation
"Newer systemd versions (v35+) do not support non-socket-activated syslog
daemons anymore and we do no longer recommend people to order their units
after syslog.target."

Signed-off-by: Tommi Kenakkala <tommi.kenakkala@oss.tieto.com>