Add Dock USB Audio Support for Samsung Car / Desk Docks

Ported from CM10, original patch: http://review.cyanogenmod.com/20586

Also includes patches:
DockAudio: Always route audio back to normal on undock.
http://review.cyanogenmod.org/24830

Bugfix: Dock events can have state greater than 1
http://review.cyanogenmod.org/24995

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Samsung docks have a non-sensing USB adio port.
Samsung get around this by having a separate Setting to route the Audio
The Changes made will only add the extra Observer if the Kernel supports the endpoint

  /sys/class/switch/dock/state

Change-Id: I8e8f5001d5c651b07bb6af496bbf806732be21fa

audio: Add overlay to fix analog docks.

Of particular interest to devices using libhardware_legacy and
affected by commit 5a484b753cc72d6a50c1dd3bbf68b3403c741a3a: http://goo.gl/rVR1Z
which restricted the routing of AUDIO_DEVICE_OUT_ANLG_DOCK_HEADSET
to docks using FORCE_ANALOG_DOCK cases. The EXTRA_DOCK_STATE_CAR case is
returning FORCE_BT_CAR_DOCK, preventing the dock audio from routing properly.

Add an overlay option for overriding to FORCE_ANALOG_DOCK.

Change-Id: Ib7d70c242aa6f537ea5d65098ceb2c591662d8bb