Use ntp.service instead of ntpd.service to start NTP services on openSUSE

systemctl enable ntpd.service is not working on openSUSE 13.1:

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% sudo systemctl enable ntpd.service
Failed to issue method call: No such file or directory
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systemctl enable ntp.service is working on openSUSE 13.1:

---snip---
% sudo systemctl enable ntp.service
ntp.service is not a native service, redirecting to /sbin/chkconfig.
[...]
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Change-Id: I1979f08786bc1ea67c011415368bf57b35e11dd7
Merge "Use ntp.service instead of ntpd.service to start NTP services on openSUSE"