[VOL-4290] Voltha go library updates for gRPC migration

Change-Id: I1aa2774beb6b7ed7419bc45aeb53fcae8a8ecda0
diff --git a/vendor/google.golang.org/protobuf/LICENSE b/vendor/google.golang.org/protobuf/LICENSE
new file mode 100644
index 0000000..49ea0f9
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/LICENSE
@@ -0,0 +1,27 @@
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+
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