dibs: change dibs_class to a const struct

The class_create() call has been deprecated in favor of class_register()
as the driver core now allows for a struct class to be in read-only
memory. Change dibs_class to be a const struct class and drop the
class_create() call.

Link: https://lore.kernel.org/all/2023040244-duffel-pushpin-f738@gregkh/

Suggested-by: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Jori Koolstra <[e-mail]>
Reviewed-by: Greg Kroah-Hartman <[e-mail]>
Reviewed-by: Alexandra Winter <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/dibs/dibs_main.c

···
 MODULE_DESCRIPTION("Direct Internal Buffer Sharing class");
 MODULE_LICENSE("GPL");
 
-static struct class *dibs_class;
+static const struct class dibs_class = {
+	.name		= "dibs",
+};
 
 /* use an array rather a list for fast mapping: */
 static struct dibs_client *clients[MAX_DIBS_CLIENTS];
···
 	if (!dibs)
 		return dibs;
 	dibs->dev.release = dibs_dev_release;
-	dibs->dev.class = dibs_class;
+	dibs->dev.class = &dibs_class;
 	device_initialize(&dibs->dev);
 
 	return dibs;
···
 {
 	int rc;
 
-	dibs_class = class_create("dibs");
-	if (IS_ERR(dibs_class))
-		return PTR_ERR(dibs_class);
+	rc = class_register(&dibs_class);
+	if (rc)
+		return rc;
 
 	rc = dibs_loopback_init();
 	if (rc)
···
 static void __exit dibs_exit(void)
 {
 	dibs_loopback_exit();
-	class_destroy(dibs_class);
+	class_unregister(&dibs_class);
 }
 
 subsys_initcall(dibs_init);