gpu: ion: Backport from CAF kk_2.7_rb1.35

*Ported dma shared buffer system
*Patched for 3.0 kernels
*Reverted "gpu: ion: Add support for CMA allocations in cp heap" to avoid a massive update to dma-mapping (we don't use CMA anyway)

NOTE: Our proprietary camera HAL was built for the old Ion API, so using the camera reboots the phone with these drivers. Potential solutions to this include creating a new HAL using CAF source or hacking the new Ion drivers somehow.

Signed-off-by: Sultanxda <sultanxda@gmail.com>