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

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

Conflicts:
	arch/arm/hotplug/intelli_plug.c

Change-Id: I7ebd99b4fb3b55c0a39d64448e86c57cac6acaea