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

Change-Id: I1aa2774beb6b7ed7419bc45aeb53fcae8a8ecda0
diff --git a/vendor/github.com/cespare/xxhash/v2/xxhash_amd64.go b/vendor/github.com/cespare/xxhash/v2/xxhash_amd64.go
new file mode 100644
index 0000000..ad14b80
--- /dev/null
+++ b/vendor/github.com/cespare/xxhash/v2/xxhash_amd64.go
@@ -0,0 +1,13 @@
+// +build !appengine
+// +build gc
+// +build !purego
+
+package xxhash
+
+// Sum64 computes the 64-bit xxHash digest of b.
+//
+//go:noescape
+func Sum64(b []byte) uint64
+
+//go:noescape
+func writeBlocks(d *Digest, b []byte) int