Try modifying the code into this:
<?php
function my_graphene_display_slider(){
global $graphene_settings;
if ( $graphene_settings['slider_disable'] || is_front_page() ) return;
if ( ! $graphene_settings['slider_position'] ) {
if ( $graphene_settings['slider_full_width'] ) add_action( 'graphene_before_content-main', 'graphene_slider' );
else add_action( 'graphene_top_content', 'graphene_slider' );
} else {
if ( $graphene_settings['slider_full_width'] ) add_action( 'graphene_after_content', 'graphene_slider' );
else add_action( 'graphene_bottom_content', 'graphene_slider', 11 );
}
}
add_action( 'template_redirect', 'my_graphene_display_slider' );