dlx: init: Fix configuration of cpu-boost sync_freq

When a thread migrates, the cpu-boost driver adds a boost to:

* the current frequency if it is less than sync_freq
* sync_freq if the current frequency is greater than sync_freq

The idea being that you want to keep it boosted but not going
crazy.  The way this was previously configured always kept it
at the current frequency which could be needlessly burning
battery power.

Change-Id: If1074294b7c55024a5820c255bf2e81d9884d2b6