The warning message
```
[config] WARNING: Ignored YAML document with GroupVersionKind ...
```
is printed for all GVKs that are not part of the kubeadm core types.
This is wrong as the component config types are supported and successfully
parsed and used despite the fact that the warning is printed for them too.
Hence this simple fix first checks if the group of the GVK is a supported
component config group and the warning is printed only if it's not.
Signed-off-by: Rostislav M. Georgiev <rostislavg@vmware.com>