sched: set sched_mc_power_savings to 2, which is the highest
 power saving possible value for this tunable. Basically according to
 http://elinux.org/images/1/1d/Comparing_Power_Saving_Techniques_For_Multicore_ARM_Platforms.pdf
 this tunable provides serious power saving improvements close to the power
 savings of hotpluging cores. Since in this Kernel we're using always a
 minimum of 2 cpus online at any time during screen off we might actually
 benefit from this because this feature packs tasks together and try to bind
 them to cpu0, which in theory will let cpu1 idle longer, thus improving
 battery life.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>