Disable Virtual Display by default in SF

These should be enabled by default once b/30022738 is resolved.

Change-Id: I70a48a0bcf98ca984a28aa130170270d16e708bf
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index de7795b..9a0cfbd 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -208,9 +208,9 @@
     mPropagateBackpressure = !atoi(value);
     ALOGI_IF(!mPropagateBackpressure, "Disabling backpressure propagation");
 
-    property_get("debug.sf.disable_hwc_vds", value, "0");
-    mUseHwcVirtualDisplays = !atoi(value);
-    ALOGI_IF(!mUseHwcVirtualDisplays, "Disabling HWC virtual displays");
+    property_get("debug.sf.enable_hwc_vds", value, "0");
+    mUseHwcVirtualDisplays = atoi(value);
+    ALOGI_IF(!mUseHwcVirtualDisplays, "Enabling HWC virtual displays");
 
     property_get("ro.sf.disable_triple_buffer", value, "0");
     mLayerTripleBufferingDisabled = !atoi(value);