msm8960: gralloc: Add workaround for Jellybean camera drivers

* adapted from display-caf
* Arcee is smarter than I am, and discovered that we can simply swap
  two fields to ensure compatibility with Jellybean camera drivers
  having the metadata fields in the private_handle_t struct.
* Enable this by defining QCOM_BSP_CAMERA_ABI_HACK.

Change-Id: Idacf457a8ba036f3b3e5d7cc5327de3c94f89727