[RTNETLINK]: Fix typo causing wrong skb to be freed

A typo introduced by myself which leads to freeing the skb
containing the netlink message when it should free the newly
allocated skb for the reply.
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/rtnetlink.c

@@ -596,7 +596,7 @@ static int rtnl_getlink(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 	err = rtnl_fill_ifinfo(nskb, dev, iw, iw_buf_len, RTM_NEWLINK,
 			       NETLINK_CB(skb).pid, nlh->nlmsg_seq, 0, 0);
 	if (err <= 0) {
-		kfree_skb(skb);
+		kfree_skb(nskb);
 		goto errout;
 	}