Bump PLATFORM_PREVIEW_SDK_VERSION to 3

Change-Id: I5a0ec062c2893bf1ac7fbec3ce98953283efcaf7
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index e384526..c481bbc 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -80,7 +80,7 @@
     # 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 := 2
+    PLATFORM_PREVIEW_SDK_VERSION := 3
   endif
 endif