Update camera HAL & implement libcamera2

* camera HAL adapted from Evervolv:
  https://github.com/Evervolv/android_hardware_qcom_camera/tree/jellybean-4.1.2

* Set TARGET_PREBUILT_LIBCAMERA := true to build only the camera HAL.

* Implements TARGET_CAMERA_SENSOR_MP_SIZE to specify default preview
  size. Defaults to 2 if unset.

* Set the 480p media profile to 320x240 size; kernel doesn't allocate enough adsp
  memory and it's not worth the trouble.

Note: libcamera source requires Froyo version of liboemcamera.so.

Change-Id: I3220c7c101af09eea242c24911d4dbf3d5e636ad