gralloc: Add workaround for Jellybean camera drivers

* 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: I2cd267dd5550404cf2e61d76fb805e780cd99d3c

Conflicts:
	libgralloc/gralloc_priv.h