Bump PLATFORM_PREVIEW_SDK_VERSION to 2

Change-Id: I6633e0077a6a89ef737d7c4b686aab033d94c41b
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 6cbe81c..4a87abb 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 := 1
+    PLATFORM_PREVIEW_SDK_VERSION := 2
   endif
 endif