DeviceSettings: audio: Add SeekBar for AnaGain3 Gain Control [WIP]
This adds a Dialog Preference which contains a seekbar to adjust the
amount of gain for AnaGain3.

It may work, it may not work. I can't test so I don't know. Just have to
test it out.

Misc: I also organised the Audio tab settings a little.
Merge pull request #18 from zwliew/cm-11.0_moaraudio

DeviceSettings: audio: Add SeekBar for AnaGain3 Gain Control [WIP]