Update Security String to 2020-02-01 bug:146378789
(cherry picked from commit 82e8e7939098ead0754dcfacab42d0452d6559d9)

Change-Id: Id48b1ed81be583c88fd3d1fbb74515f16c86c681
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index bf84eb1..6e72f2c 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -250,7 +250,7 @@
     #  It must be of the form "YYYY-MM-DD" on production devices.
     #  It must match one of the Android Security Patch Level strings of the Public Security Bulletins.
     #  If there is no $PLATFORM_SECURITY_PATCH set, keep it empty.
-      PLATFORM_SECURITY_PATCH := 2020-01-05
+      PLATFORM_SECURITY_PATCH := 2020-02-01
 endif
 .KATI_READONLY := PLATFORM_SECURITY_PATCH