Update security string to 2016-09-07 to platform and CTS for September   respin am: cc5148493f am: 637fa9c4c5 am: 5ed4043667 am: 48e00645fe am: f63dfac0e3
am: a14e8c2f31

Change-Id: I471611e0996ab801d105a392fafbb8c1008c3350
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 6710f2c..87444c3 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -73,7 +73,7 @@
   # Can be an arbitrary string, but must be a single word.
   #
   # If there is no $PLATFORM_SECURITY_PATCH set, keep it empty.
-  PLATFORM_SECURITY_PATCH := 2016-09-05
+  PLATFORM_SECURITY_PATCH := 2016-09-07
 endif
 
 ifeq "" "$(PLATFORM_BASE_OS)"