Favicon URL in multisite

functions.php

add_filter( 'genesis_favicon_url', 'customize_favicon_url' );
/**
 * Change location of favicon reference.
 * 
 * @since 1.0.0
 * 
 * @global int $blog_id Current blog ID.
 * 
 * @return string Updated favicon URL.
 */
function customize_favicon_url() {
	
	if ( ! is_multisite() ) {
		$favicon = CHILD_URL . '/images/favicon.ico';
	} else {
		global $blog_id;
		$favicon = CHILD_URL . '/images/favicon-' . $blog_id . '.ico';
	}
	
	return esc_url( $favicon );
	
}