Clarify brightness correction API

Add annotations to clarify the brightness
correction API.

Bug: 125347154
Test: atest android.display.cts.BrightnessTest
Test: manual, flash phone, get app using API to push corrections, adb shell dumpsys display
Change-Id: Icbb61bb542a49c49f279b865d69d59a542c0e42b
4 files changed