kubeadm token create --print-join-command --config <path>
fails with Error: can not mix '--config' with arguments [print-join-command]
As print-joint command can't be put into the configuration file it
should be possible to use those 2 options at the same time.
Added print-join-command options to the list of exceptions in
ValidateMixedArguments check to allow its usage with --config option.
Fixes: kubernetes/kubeadm#1166
eacff9436e