net: use dev->name in netdev_pr* when it's available

netdev_name() returns dev->name only when the net_device is in
NETREG_REGISTERED state.

However, dev->name is always populated on creation, so we can easily use
it.

There are two cases when there's no real name - when it's an empty string
or when the name is in form of "eth%d", then netdev_name() returns "unnamed
net_device".

CC: "David S. Miller" <davem@davemloft.net>
CC: Tom Gundersen <teg@jklm.no>
Signed-off-by: NVeaceslav Falico <vfalico@gmail.com>
Acked-by: NTom Gundersen <teg@jklm.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -3383,8 +3383,8 @@ extern struct pernet_operations __net_initdata loopback_net_ops;
 
 static inline const char *netdev_name(const struct net_device *dev)
 {
-	if (dev->reg_state != NETREG_REGISTERED)
-		return "(unregistered net_device)";
+	if (!dev->name[0] || strchr(dev->name, '%'))
+		return "(unnamed net_device)";
 	return dev->name;
 }