op-mode: T6715: manually changing time/date is not synced into hardware clock

When not using NTP and adjusting the current system time/date using set date
the time is not saved across a reboot into the hardware RTC. This commit
explicitly syncs the current time after a change into the systems RTC.

Most routers do not run without NTP (which is even a VyOS default) so the
priority is pretty low.

(cherry picked from commit 835126e)

Author: c-po

op-mode-definitions/date.xml.in

@@ -35,7 +35,7 @@
             <list>&lt;MMDDhhmm&gt; &lt;MMDDhhmmYY&gt; &lt;MMDDhhmmCCYY&gt; &lt;MMDDhhmmCCYY.ss&gt;</list>
           </completionHelp>
         </properties>
-        <command>/bin/date "$3"</command>
+        <command>sudo bash -c "/bin/date '$3' &amp;&amp; hwclock --systohc --localtime"</command>
       </tagNode>
     </children>
   </node>