PLATFORM_PREVIEW_SDK_VERSION == 4 for DP4

Bug: 27150977
Change-Id: I0958ee2cc377c5640c616dab8f093323ffd76c29
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 318abd3..363a0d4 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -91,7 +91,7 @@
     # assuming the device can only support APIs as of the previous official
     # public release.
     # This value will always be 0 for release builds.
-    PLATFORM_PREVIEW_SDK_VERSION := 3
+    PLATFORM_PREVIEW_SDK_VERSION := 4
   endif
 endif