RC: option to toggle dimming of the notification shade (2/2) - picked from Xylon rom

        Allow the user to enable/disable dimming of the notification shade
        pulldown. Check isHighEndGfx() to respect the default setting that
        the device currently supports.

        Users on low-end device may want to have this feature, while users
        on high-end devices may want to disable it (possible battery life
        savings and what not).

        Change-Id: I661254ec7ae1548707d94f5d41efe877554c6023