net: dcb: set error code on failures

In function dcbnl_cee_fill(), returns the value of variable err on
errors. However, on some error paths (e.g. nla put fails), its value may
be 0. It may be better to explicitly set a negative errno to variable
err before returning.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=188881Signed-off-by: NPan Bian <bianpan2016@163.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/dcb/dcbnl.c

@@ -1353,6 +1353,7 @@ static int dcbnl_cee_fill(struct sk_buff *skb, struct net_device *netdev)
 dcb_unlock:
 	spin_unlock_bh(&dcb_lock);
 nla_put_failure:
+	err = -EMSGSIZE;
 	return err;
 }