Update Security String to 2016-02-01

b/26110717

Change-Id: I1085f5d053b07c6c81d2ef22fbba5ab9157a67f2
(cherry picked from commit f0f73c06e25e17ecf8e06f42c51efac102597f57)
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 2939224..bf9b2e8 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -103,7 +103,7 @@
   # 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 := 2016-01-01
+  PLATFORM_SECURITY_PATCH := 2016-02-01
 endif
 
 ifeq "" "$(PLATFORM_BASE_OS)"