Fix staging/src/k8s.io/apimachinery/pkg/labels golint findings
Fix staging/src/k8s.io/apimachinery/pkg/labels golint findings

Signed-off-by: ialidzhikov <i.alidjikov@gmail.com>

Kubernetes-commit: 88fadb24c1a954ecb43e190beb6e745eee36e204

kubernetes/api