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

Change-Id: I1aa2774beb6b7ed7419bc45aeb53fcae8a8ecda0
diff --git a/vendor/github.com/google/btree/btree.go b/vendor/github.com/google/btree/btree.go
index 6ff062f..b83acdb 100644
--- a/vendor/github.com/google/btree/btree.go
+++ b/vendor/github.com/google/btree/btree.go
@@ -796,7 +796,7 @@
 }
 
 // DescendGreaterThan calls the iterator for every value in the tree within
-// the range (pivot, last], until iterator returns false.
+// the range [last, pivot), until iterator returns false.
 func (t *BTree) DescendGreaterThan(pivot Item, iterator ItemIterator) {
 	if t.root == nil {
 		return