intelli_plug: add dynamic load sampling rate logic

Add dynamic sampling logic based on load. If load is high and required more
than 2 cores, increase the sampling rate for a duration of 3 seconds to help
manage the load better during this time.  Once duration expires, revert back
to lazier sampling rate for better batter performance.

Change-Id: I83e1884151431d19b19a24059643e1ecad4e31bb