py3: can_read: attributelevelrights is already string

Remove decode() as it causes error in py3 because the attribute is
already string not bytes

https://fedorahosted.org/freeipa/ticket/4985

Reviewed-By: Christian Heimes <cheimes@redhat.com>

ipaserver/plugins/ldap2.py

@@ -310,7 +310,7 @@ class ldap2(CrudBackend, LDAPClient):
 
         attrs = self.get_effective_rights(dn, [attr])
         if 'attributelevelrights' in attrs:
-            attr_rights = attrs.get('attributelevelrights')[0].decode('UTF-8')
+            attr_rights = attrs.get('attributelevelrights')[0]
             (attr, rights) = attr_rights.split(':')
             if 'w' in rights:
                 return True