Bug 1447284

This bug is created as a clone of upstream ticket:
https://pagure.io/freeipa/issue/6920

During an upgrade from IPA 4.1, when upgrade script attempts to enable KDC proxy by creating an LDAP entry in `cn=KDC,cn=vm,cn=master,cn=ipa,cn=etc,dc=example,dc=com` it fails, because the parent entry does not exist.

This is a regression was introduced by b1a1e104391c84cb9af7b0a7c8748c8652442ddb

/var/log/ipaupgrade.log

```
2017-05-02T07:11:19Z DEBUG   File "/usr/lib/python2.7/site-packages/ipapython/admintool.py", line 172, in execute
    return_value = self.run()
  File "/usr/lib/python2.7/site-packages/ipaserver/install/ipa_server_upgrade.py", line 46, in run
    server.upgrade()
  File "/usr/lib/python2.7/site-packages/ipaserver/install/server/upgrade.py", line 1869, in upgrade
    upgrade_configuration()
  File "/usr/lib/python2.7/site-packages/ipaserver/install/server/upgrade.py", line 1658, in upgrade_configuration
    http.enable_kdcproxy()
  File "/usr/lib/python2.7/site-packages/ipaserver/install/httpinstance.py", line 437, in enable_kdcproxy
    'KDC', self.fqdn, [u'kdcProxyEnabled'], self.suffix)
  File "/usr/lib/python2.7/site-packages/ipaserver/install/service.py", line 214, in set_service_entry_config
    api.Backend.ldap2.add_entry(entry)
  File "/usr/lib/python2.7/site-packages/ipapython/ipaldap.py", line 1504, in add_entry
    self.conn.add_s(str(entry.dn), list(attrs.items()))
  File "/usr/lib64/python2.7/contextlib.py", line 35, in __exit__
    self.gen.throw(type, value, traceback)
  File "/usr/lib/python2.7/site-packages/ipapython/ipaldap.py", line 966, in error_handler
    raise errors.NotFound(reason=arg_desc or 'no such entry')
```