Add makestep in chrony.conf

Normally chronyd will cause the system to gradually correct any time offset, by slowing down or speeding up the clock as required.
In certain situations, the system clock might be so far adrift
that this slewing process would take a very long time to correct the system clock

Change-Id: I939b6aae1dbeb133203085ec68bdb9f7936ee9ef
Closes-Bug: #1696056