bump version from 2.2 to 2.2.1 for next froyo release

Change-Id: Ic636f111d4a7a69954539bbd480b7119bf0d730f
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index ec5dcd4..df5cc09 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -41,7 +41,7 @@
   # which is the version that we reveal to the end user.
   # Update this value when the platform version changes (rather
   # than overriding it somewhere else).  Can be an arbitrary string.
-  PLATFORM_VERSION := 2.2
+  PLATFORM_VERSION := 2.2.1
 endif
 
 ifeq "" "$(PLATFORM_SDK_VERSION)"