gralloc: Allow legacy devices to use PMEM for ADSP (camera).

Partially bring back PMEM support for legacy devices having proprietary camera
libraries stuck in PMEM. This change allows these devices to continue using
PMEM for the camera, and ION for everything else.

Change-Id: I1afbc7d137b3d49b2ab3e53917b16fd920ea140b
libgralloc: alloc_controller.h: Use smart pointer for PmemAdspAlloc

I have no idea what I'm doing.
pmemalloc: Fix compilation

Thanks to professorpasta on XDA for pointing out why it wasn't compiling.
libgralloc: Add back support for PMEM SMI

Needed for our PMEM video controller and PMEM camera libs.

Signed-off-by: Sultanxda <sultanxda@gmail.com>
librgralloc: gralloc_priv.h: Define GRALLOC_USAGE_PRIVATE_SECURE_DISPLAY