Use new HWC display type/count constants.

Change-Id: I774d0c68906ac6dc69268f708c30a6b0868b8816
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index ce096d3..0906f80 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -421,7 +421,7 @@
     EGLConfig mEGLConfig;
     EGLDisplay mEGLDisplay;
     EGLint mEGLNativeVisualId;
-    sp<IBinder> mBuiltinDisplays[DisplayDevice::NUM_DISPLAY_TYPES];
+    sp<IBinder> mBuiltinDisplays[DisplayDevice::NUM_BUILTIN_DISPLAY_TYPES];
 
     // Can only accessed from the main thread, these members
     // don't need synchronization