Downgrade Kubernetes vendor version

Multus community decide that multus support the Kubernetes that
Kubernetes community supports, so changed vendor code to the
oldest version of currently supported.

vendor/golang.org/x/sys/unix/dev_zos.go

@@ -1,29 +0,0 @@
-// Copyright 2020 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build zos && s390x
-// +build zos,s390x
-
-// Functions to access/create device major and minor numbers matching the
-// encoding used by z/OS.
-//
-// The information below is extracted and adapted from <sys/stat.h> macros.
-
-package unix
-
-// Major returns the major component of a z/OS device number.
-func Major(dev uint64) uint32 {
-	return uint32((dev >> 16) & 0x0000FFFF)
-}
-
-// Minor returns the minor component of a z/OS device number.
-func Minor(dev uint64) uint32 {
-	return uint32(dev & 0x0000FFFF)
-}
-
-// Mkdev returns a z/OS device number generated from the given major and minor
-// components.
-func Mkdev(major, minor uint32) uint64 {
-	return (uint64(major) << 16) | uint64(minor)
-}