net: rtnetlink: unify the code in __rtnl_newlink get dev with the rest

__rtnl_newlink() code flow is a bit different around tb[IFLA_IFNAME]
processing comparing to the other places. Change that to be unified with
the rest.
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/rtnetlink.c

@@ -3080,12 +3080,10 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 	ifm = nlmsg_data(nlh);
 	if (ifm->ifi_index > 0)
 		dev = __dev_get_by_index(net, ifm->ifi_index);
-	else {
-		if (ifname[0])
-			dev = __dev_get_by_name(net, ifname);
-		else
-			dev = NULL;
-	}
+	else if (tb[IFLA_IFNAME])
+		dev = __dev_get_by_name(net, ifname);
+	else
+		dev = NULL;
 
 	if (dev) {
 		master_dev = netdev_master_upper_dev_get(dev);