msm: msm_rq_stats: Tone down mpdecision

Add a new Kconfig to enable more conservative computations sent
to mpdecision:

 * Do a time window weighted load computation instead of just a sum
 * Do an sliding window averaged time computation for number runnable

The purpose of these changes is to make mpdecision less likely to
keep extra cores online.  It currently has a tendancy to run more
cores running than needed and this can even cause some lag issues.

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>