Camera: fix panorama preview on older devices

When PREVIEW_FBO_WIDTH_SCALE is set to 4, the preview FBO becomes
larger than older GPUs can handle. Detect it and reduce the value
to 2 like on pre-KitKat releases.

Change-Id: I2a2f72347de045f4489b156bdf0d4a67ae46e1a1
Camera2: enable antibanding by default

The default for antibanding should be "auto", otherwise there will
be banding effect when taking photos in certain lighting.

Normally, the default on most devices is "auto" (depends on Camera
HAL). But the code from CAF changed it so that the Camera app
explicitly change it to "off".

Change-Id: I3f1576ef85117ddb653816f48437eb7dc8b83b39
camera: ZSL and focus fixes

 * Drop the use of the touchaf-aec parameter entirely. No camera needs
   this anymore.
 * Only autofocus before a snap if we are actually in "auto" mode.
 * Change ZSL from a preference to an overlay boolean.

Change-Id: I2eb47b3816b18b73b73053629bea98ce0800d27c
Camera2: Preview needs to be stopped when changing resolution

This was done in startPreview as a hack, but was removed in
f729b85e12cfa2674048d8cce2f724014b8fc910. Specifically add it
back when the resolution is changed.

Change-Id: I306abd788bafdff4e6fba7eec4e6ff05bb3cc47c