intelli_plug: refactor stats calculation code to be less intrusive
this is done for those kernels which do not have 100% source code available
and must use existing closed source modules such as wifi drivers

Change-Id: Ia0f58470e91a30bb5f1ca4a4995bf4e4f68e6ff8
Signed-off-by: Paul Reioux <reioux@gmail.com>