dummy: declare dummy devices as enumerated devices

Dummy device name is enumerated by the kernel, let user space be aware
of the naming scheme used by dummy devices:
(visible in /sys/class/net/<iface>/name_assign_type).
Signed-off-by: NZhang Shengju <zhangshengju@cmss.chinamobile.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/dummy.c

@@ -388,7 +388,7 @@ static int __init dummy_init_one(void)
 	int err;
 
 	dev_dummy = alloc_netdev(sizeof(struct dummy_priv),
-				 "dummy%d", NET_NAME_UNKNOWN, dummy_setup);
+				 "dummy%d", NET_NAME_ENUM, dummy_setup);
 	if (!dev_dummy)
 		return -ENOMEM;