gralloc: Change private usage flags from enums to defines

1. It helps in checking gralloc private usage flags at compile time.
2. Define GRALLOC_MODULE_PERFORM_GET_UBWC_FLAG to enable client to
   query the value of "PRIV_FLAGS_UBWC_ALIGNED" flag at run time.
3. Add ADRENO_PIXELFORMAT_NV12_EXT in defined Adreno Pixel formats
   to fix NV12_UBWC HAL pixel format conversion to Adreno format.

Change-Id: I78ccac98f1bd1bfbd2aa596ceb7a293f3d2e5f6e

libgralloc/alloc_controller.cpp

@@ -308,9 +308,10 @@ ADRENOPIXELFORMAT AdrenoMemInfo::getGpuPixelFormat(int hal_format)
         case HAL_PIXEL_FORMAT_sRGB_A_8888:
             return ADRENO_PIXELFORMAT_R8G8B8A8_SRGB;
         case HAL_PIXEL_FORMAT_NV12_ENCODEABLE:
+            return ADRENO_PIXELFORMAT_NV12;
         case HAL_PIXEL_FORMAT_YCbCr_420_SP_VENUS:
         case HAL_PIXEL_FORMAT_YCbCr_420_SP_VENUS_UBWC:
-            return ADRENO_PIXELFORMAT_NV12;
+            return ADRENO_PIXELFORMAT_NV12_EXT;
         default:
             ALOGE("%s: No map for format: 0x%x", __FUNCTION__, hal_format);
             break;