ethtool: Remove redundant ret assignments

The assignment here will be overwritten, so it should be deleted

The clang_analyzer complains as follows:

net/ethtool/netlink.c:

Value stored to 'ret' is never read

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: luo penghao <luo.penghao@zte.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ethtool/netlink.c

@@ -638,7 +638,6 @@ static void ethnl_default_notify(struct net_device *dev, unsigned int cmd,
 	if (ret < 0)
 		goto err_cleanup;
 	reply_len = ret + ethnl_reply_header_size();
-	ret = -ENOMEM;
 	skb = genlmsg_new(reply_len, GFP_KERNEL);
 	if (!skb)
 		goto err_cleanup;