hwc: Add support for RGBA_4444 and RGBA_5551 formats

1. Modify gralloc library to allocate buffers for RGBA_4444 and
   RGBA_5551 formats
2. Modify copybit library to add composition support for RGBA_4444
   and RGBA_5551 layers
3. Modify hwc library to add MDP composition and rotator support for
   RGBA_4444 and RGBA_5551 layers.

Change-Id: I30dbc4e5e2c010835fa7e7663f996f67779a1803
4 files changed