Mark mAutomaticBrightnessController @Nullable.

Check that AutomaticBrightnessController is not null before calling update() and resetShortTermModel().

Bug: 203737431
Test: manual: flashed build with automaticBrightnessController set to null and verified that no NPE is thrown.
Change-Id: Ie709d4bc7e6166eeb7e936bea79162f468c713f4
1 file changed