Release tag 4.1.5 for voltha-2.9

Change-Id: I272708f4f4caeac6793dc71c7b33cd4d7833a6d0
diff --git a/VERSION b/VERSION
index 6f2dee9..b1cbc1f 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-4.1.5-dev
+4.1.5