client: make statestore and fstore consistent with server
    
    There should not be mixed statestore as global variable and as local
    function parameter. This commit fixes usage of sysrestore and statestore
    as local variables only. In future we may need to change default
    statestore and fstore depending on where the functions are called and
    this change makes it easier and less error prone.
    
    https://fedorahosted.org/freeipa/ticket/6392
    
    Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>