BrightnessChangeEvent works for increasing brightness

BrightnessChangeEvents were only sending when decreasing the brightness.
Due to two issues:
1) brightness adjustment was being clamped to 0-1 instead of -1 to +1.
(meaning buggy conditions were met when 0.0 == 0.0)
2) the brightness reason that was being read was the old reason,
rather than the temporary (new) reason (meaning we were not sending
change events correctly).

Bug: 282005647
Test: adb shell dumpsys | grep BrightnessChangeEvent
Change-Id: I2ada97469b68baee695e06db0c8a0cdbbab1027f