IFP: Use subreq, not req when calling RefreshRules_recv
    
    This emits a failure when refreshing access control rules from e.g.
    sssctl access-report.
    
    Resolves:
    https://pagure.io/SSSD/sssd/issue/3874
    
    Reviewed-by: Pavel Březina <pbrezina@redhat.com>