Rename mBrighteningLuxThreshold to mAmbientBrighteningThreshold in ABC

log info.

the global variant mBrighteningLuxThreshold in the log info is not exist,
it's more reasonable to change mBrighteningLuxThreshold to mAmbientBrighteningThreshold.

Bug: 274655714

Test:
1. adb shell cmd display ab-logging-enable
2. adb logcat | grep updateAmbientLux

Change-Id: I88b0425b9f638cf0e20d175a7cbe283a54816852
Signed-off-by: jiayongqiang <jiayongqiang@xiaomi.com>