fix DimLayer in GLES2.0 SF

DimLayer state wasn't initialized properly.

Bug: 10442967
Change-Id: I384c1d85c58c96ae29d5daa1fabee9f4ce003501
diff --git a/services/surfaceflinger/RenderEngine/GLES20RenderEngine.cpp b/services/surfaceflinger/RenderEngine/GLES20RenderEngine.cpp
index dcad390..cde1e3a 100644
--- a/services/surfaceflinger/RenderEngine/GLES20RenderEngine.cpp
+++ b/services/surfaceflinger/RenderEngine/GLES20RenderEngine.cpp
@@ -116,7 +116,11 @@
 }
 
 void GLES20RenderEngine::setupDimLayerBlending(int alpha) {
-    mState.setPlaneAlpha(alpha / 255.0f);
+    mState.setPlaneAlpha(1.0f);
+    mState.setPremultipliedAlpha(true);
+    mState.setOpaque(false);
+    mState.setColor(0, 0, 0, alpha/255.0f);
+    mState.disableTexture();
 
     if (alpha == 0xFF) {
         glDisable(GL_BLEND);
@@ -124,7 +128,6 @@
         glEnable(GL_BLEND);
         glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
     }
-    disableTexturing();
 }
 
 void GLES20RenderEngine::setupLayerTexturing(const Texture& texture) {