[k8s.io/sample-controller/controller.go]: fixup minor typo
[k8s.io/sample-controller/controller.go]: fixup minor typo

Signed-off-by: Zhou Peng <p@ctriple.cn>

Kubernetes-commit: 5616ce97622e25a90f89f56e5556e73e065ee012

kubernetes/sample-controller,kubernetes/sample-controller