Add back backlight brightness curve adjustment.

Settings part for this really really awesome work from Danny @cm

- new settings point in ASS->Display Brightness
- if auto brightness is selected you can change options with adjust
- change hysterse on each level
- add or split levels with longpress
- change ambients range

- also this commit resort and cleaned up a bit our ass display settings

cheers

Change-Id: I174cc7bc93f7cf6e0eb958fc275f4c1c9e588001