[VOL-5245] branch and release repo:voltha-lib-go

Makefile
makefiles/*
pkg/*
--------------------------
  o Update copyright notice ending date to span the current year.
  o Copyright update will force running a jenkins job to sanity check the repo.

VERSION
-------
  o Remove *-dev suffix in prepration for creation a release branch.

Change-Id: I1ca9e7d54b1669f2a4556a0d10dac34e29079d63
diff --git a/VERSION b/VERSION
index d352daf..a5f017a 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-7.5.1-dev
+7.5.1