A quick search reveals that only 1 device uses this - kona.
Instead of adding a system prop for this, that one device
can add its own AdaptiveBacklight class. This allows kona to
use AdaptiveBacklight without having to modify the common class.
This reverts commit c11396ecc6738126e84f6262fecbd6021ca20abd.
Change-Id: Id912091f64da39a10d30c9770f248cf6467e8760
Zhao Wei Liew