dcbnl: Silence harmless gcc warning about uninitialized reply_nlh

Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/dcb/dcbnl.c

@@ -1664,7 +1664,7 @@ static int dcb_doit(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 	u32 pid = skb ? NETLINK_CB(skb).pid : 0;
 	int ret = -EINVAL;
 	struct sk_buff *reply_skb;
-	struct nlmsghdr *reply_nlh;
+	struct nlmsghdr *reply_nlh = NULL;
 	const struct reply_func *fn;
 
 	if (!net_eq(net, &init_net))