sdm: Add property to handle HDR

- Set "sys.hwc_disable_hdr" to 1 to disable HDR handling
  in HAL.
- On setting that property, a HDR layer will be treated
  as a regular layer.

Change-Id: I3309c0ec29dc1b3c56294f1bf3e542977235c475
Crs-fixed: 1114932
2 files changed