Actually apply color transform for GPU comp.

Bug: 129573282
Test: boots
Change-Id: I0a2f9c87fd2eb09ea9c343d5ec9b309644aaeb8b
diff --git a/services/surfaceflinger/CompositionEngine/src/Output.cpp b/services/surfaceflinger/CompositionEngine/src/Output.cpp
index d22bdaf..2893031 100644
--- a/services/surfaceflinger/CompositionEngine/src/Output.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/Output.cpp
@@ -98,6 +98,7 @@
     }
 
     mState.colorTransform = newColorTransform;
+    mState.colorTransformMat = transform;
 
     dirtyEntireOutput();
 }