ipv6: fix error propagation in ip6_ufo_append_data()

We should return errcode from sock_alloc_send_skb()
Signed-off-by: NZheng Yan <zheng.z.yan@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/ip6_output.c

@@ -1123,7 +1123,7 @@ static inline int ip6_ufo_append_data(struct sock *sk,
 			hh_len + fragheaderlen + transhdrlen + 20,
 			(flags & MSG_DONTWAIT), &err);
 		if (skb == NULL)
-			return -ENOMEM;
+			return err;
 
 		/* reserve space for Hardware header */
 		skb_reserve(skb, hh_len);