Automatic merge from submit-queue

kubeadm: Migrate to client-go

**What this PR does / why we need it**: Finish the migration for kubeadm to use client-go wherever possible

**Which issue this PR fixes**: fixes #https://github.com/kubernetes/kubeadm/issues/52

**Special notes for your reviewer**: /cc @luxas @pires 

**Release note**:
```release-note
NONE
```