Settings: Add TouchKey Light Duration Pref

Gives the option to change duration of touchkey backlights

Must be enabled in overlay

Patchset 4:
- correted some errors
- changed some unsused stuff on other settings....just minor

Patchset 5
- found a tab lol

Change-Id: I75d7effe492e25919601a4d4793e75400f814c67