kubeadm: fix the lint failure where return value is not checked

Signed-off-by: SataQiu <1527062125@qq.com>

cmd/kubeadm/app/cmd/phases/workflow/runner.go

@@ -338,8 +338,7 @@ func (e *Runner) BindToCommand(cmd *cobra.Command) {
 			RunE: func(cmd *cobra.Command, args []string) error {
 				// if the phase has subphases, print the help and exits
 				if len(p.Phases) > 0 {
-					cmd.Help()
-					return nil
+					return cmd.Help()
 				}
 
 				// overrides the command triggering the Runner using the phaseCmd