net: fix unreleased lock in cable test

fix an unreleased lock in out_dev_put path by removing the (now)
unnecessary path.

Reported-by: syzbot+c641161e97237326ea74@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=c641161e97237326ea74
Fixes: 3688ff30 ("net: ethtool: cable-test: Target the command to the requested PHY")
Signed-off-by: Diogo Jahchan Koike <djahchankoike@gmail.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20240826134656.94892-1-djahchankoike@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/ethtool/cabletest.c

@@ -77,7 +77,7 @@ int ethnl_act_cable_test(struct sk_buff *skb, struct genl_info *info)
 				      info->extack);
 	if (IS_ERR_OR_NULL(phydev)) {
 		ret = -EOPNOTSUPP;
-		goto out_dev_put;
+		goto out_rtnl;
 	}
 
 	ops = ethtool_phy_ops;
@@ -99,7 +99,6 @@ int ethnl_act_cable_test(struct sk_buff *skb, struct genl_info *info)
 
 out_rtnl:
 	rtnl_unlock();
-out_dev_put:
 	ethnl_parse_header_dev_put(&req_info);
 	return ret;
 }