Thermal: Introduce fair_share thermal governor

This patch introduces a simple 'weight' based
governor named fair_share governor. Whenever the
thermal framework gets notified of the trip point
violation, this governor (if configured), throttles
the cooling devices associated with a thermal zone.

This mapping between a thermal zone and a cooling device
and the effectiveness of cooling are provided in the
platform layer.

Signed-off-by: Durgadoss R <durgadoss.r@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>