get rid of Surface::getISurfaceTexture()

this was there just for legacy reasons.

Change-Id: I0a48d6e04d7efa65033f9f10c91bba557f16ae8b
diff --git a/libs/gui/tests/SurfaceTextureClient_test.cpp b/libs/gui/tests/SurfaceTextureClient_test.cpp
index 58ae170..24b60f1 100644
--- a/libs/gui/tests/SurfaceTextureClient_test.cpp
+++ b/libs/gui/tests/SurfaceTextureClient_test.cpp
@@ -112,7 +112,7 @@
 };
 
 TEST_F(SurfaceTextureClientTest, GetISurfaceTextureIsNotNull) {
-    sp<IGraphicBufferProducer> ist(mSTC->getISurfaceTexture());
+    sp<IGraphicBufferProducer> ist(mSTC->getIGraphicBufferProducer());
     ASSERT_TRUE(ist != NULL);
 }