s390/netiucv: Make use of iucv_alloc_device()

Make use of iucv_alloc_device() to get rid of quite some code. In addition
this also removes a cast to an incompatible function (clang W=1):

drivers/s390/net/netiucv.c:1716:18: error: cast from 'void (*)(const void *)' to 'void (*)(struct device *)' converts to incompatible function type [-Werror,-Wcast-function-type-strict]
1716 | dev->release = (void (*)(struct device *))kfree;
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Reported-by: Nathan Chancellor <[e-mail]>
Closes: https://lore.kernel.org/r/[e-mail]
Acked-by: Alexandra Winter <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Heiko Carstens <[e-mail]>
Signed-off-by: Alexander Gordeev <[e-mail]>

drivers/s390/net/netiucv.c

···
 static int netiucv_register_device(struct net_device *ndev)
 {
 	struct netiucv_priv *priv = netdev_priv(ndev);
-	struct device *dev = kzalloc(sizeof(struct device), GFP_KERNEL);
+	struct device *dev;
 	int ret;
 
 	IUCV_DBF_TEXT(trace, 3, __func__);
 
-	if (dev) {
-		dev_set_name(dev, "net%s", ndev->name);
-		dev->bus = &iucv_bus;
-		dev->parent = iucv_root;
-		dev->groups = netiucv_attr_groups;
-		/*
-		 * The release function could be called after the
-		 * module has been unloaded. It's _only_ task is to
-		 * free the struct. Therefore, we specify kfree()
-		 * directly here. (Probably a little bit obfuscating
-		 * but legitime ...).
-		 */
-		dev->release = (void (*)(struct device *))kfree;
-		dev->driver = &netiucv_driver;
-	} else
+	dev = iucv_alloc_device(netiucv_attr_groups, &netiucv_driver, NULL,
+				"net%s", ndev->name);
+	if (!dev)
 		return -ENOMEM;
 
 	ret = device_register(dev);