[RenderEngine] Cleanup Description.

Make Description a struct.

Minor: Use mat4 instead of mat3.

BUG: 112585051
Test: Build, flash and boot
Change-Id: I8f4b8ac1fd847239b42af9685ba0cddb15f0fac7
diff --git a/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.h b/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.h
index 1abc5ba..94a4bba 100644
--- a/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.h
+++ b/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.h
@@ -131,9 +131,9 @@
 
     mat4 mSrgbToDisplayP3;
     mat4 mDisplayP3ToSrgb;
-    mat3 mSrgbToXyz;
-    mat3 mBt2020ToXyz;
-    mat3 mDisplayP3ToXyz;
+    mat4 mSrgbToXyz;
+    mat4 mBt2020ToXyz;
+    mat4 mDisplayP3ToXyz;
     mat4 mXyzToSrgb;
     mat4 mXyzToDisplayP3;
     mat4 mXyzToBt2020;