Fix regression: TextureView.setAlpha() was ignored

Change-Id: I9f43eec0fe23a65dcc1cf9cd0ac1f5e8907786a7
diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index 0daf9c7..6e8e126 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -1061,7 +1061,7 @@
 }
 
 void OpenGLRenderer::drawTextureLayer(Layer* layer, const Rect& rect) {
-    float alpha = layer->getAlpha() / 255.0f * mSnapshot->alpha;
+    float alpha = getLayerAlpha(layer);
 
     setupDraw();
     if (layer->getRenderTarget() == GL_TEXTURE_2D) {