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
diff --git a/libcopybit/copybit.cpp b/libcopybit/copybit.cpp
index bd9fc1a..421f531 100644
--- a/libcopybit/copybit.cpp
+++ b/libcopybit/copybit.cpp
@@ -126,6 +126,8 @@
 static int get_format(int format) {
     switch (format) {
         case HAL_PIXEL_FORMAT_RGB_565:       return MDP_RGB_565;
+        case HAL_PIXEL_FORMAT_RGBA_5551:     return MDP_RGBA_5551;
+        case HAL_PIXEL_FORMAT_RGBA_4444:     return MDP_RGBA_4444;
         case HAL_PIXEL_FORMAT_RGBX_8888:     return MDP_RGBX_8888;
         case HAL_PIXEL_FORMAT_BGRX_8888:     return MDP_BGRX_8888;
         case HAL_PIXEL_FORMAT_RGB_888:       return MDP_RGB_888;