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: I9aaba7ce9f9bc9bac5da38605e6a2bb2a94d4277
Signed-off-by: Paul Reioux <reioux@gmail.com>