typo: Error out if the policy is already set in policy update cmd (#3931)
typo: Error out if the policy is already set in policy update cmd (#3931)

Fix a typo when checking if a policy is already set to a user or a
group.
vadmeste/mc,minio/mc,balamurugana/mc,vadmeste/mc,krisis/mc,balamurugana/mc,minio/mc,krisis/mc