Issue #337 Remove rerr = nil from the defer function

Current code for handling error in the configureCluster function is wrong
and return nil even there is an error because of the way we handled in the
defer function.

Following snip will always return the `nil` since it is assigned to `nil`
at the end of defer function.

```
package main

import (
        "fmt"
)

func getError() (rerr error) {
        defer func(){
                err := fmt.Errorf("Error from defer")
                if err != nil {
                    rerr = err
                }
                rerr = nil
        }()
        return fmt.Errorf("My error should be returned")
}

func main() {
        fmt.Println(getError())
}
```

pkg/crc/machine/machine.go

@@ -694,7 +694,6 @@ func configureCluster(ocConfig oc.OcConfig, sshRunner *crcssh.SSHRunner, pullSec
 		if err := cluster.StopAndRemovePodsInVM(sshRunner); err != nil {
 			rerr = err
 		}
-		rerr = nil
 	}()
 
 	logging.Info("Adding user's pull secret ...")