hwc2: Add support for HDR and HWC tonemapping

- Identify HDR layer in HWC, and add support to handle
  tonemap requests from  SDM
- Include hwc tonemapper which tonemaps layers using the
  gpu tonemapper
- Add hint in BufferAllocator to specify gfx client

Change-Id: I45a2182fa96e366600d81cdb4cb08bceff3bfcb8
Crs-fixed: 2036626
7 files changed