get rid of HAL pixelformats 5551 and 4444

Change-Id: I196ee30ed57707ed4cc46fb3a9c5c07c5bac6fff
diff --git a/modules/gralloc/gralloc.cpp b/modules/gralloc/gralloc.cpp
index 99aeb01..a2dec6b 100644
--- a/modules/gralloc/gralloc.cpp
+++ b/modules/gralloc/gralloc.cpp
@@ -217,8 +217,6 @@
             bpp = 3;
             break;
         case HAL_PIXEL_FORMAT_RGB_565:
-        case HAL_PIXEL_FORMAT_RGBA_5551:
-        case HAL_PIXEL_FORMAT_RGBA_4444:
         case HAL_PIXEL_FORMAT_RAW_SENSOR:
             bpp = 2;
             break;