always by default show welcome panel in the dashboard

thanks @birgire with your help i change the code to make this work.

everyone that looking for the same solution you can use this code:

 add_action( 'load-index.php', 'show_welcome_panel' );

function show_welcome_panel() {
    $user_id = get_current_user_id();

    if ( 1 != get_user_meta( $user_id, 'show_welcome_panel', true ) )
        update_user_meta( $user_id, 'show_welcome_panel', 1 );
}