udp: remove unreachable ufo branches

Remove two references to ufo in the udp send path that are no longer
reachable now that ufo has been removed.

Commit 85f1bd9a7b5a ("udp: consistently apply ufo or fragmentation")
is a fix to ufo. It is safe to revert what remains of it.

Also, no skb can enter ip_append_page with skb_is_gso true now that
skb_shinfo(skb)->gso_type is no longer set in ip_append_page/_data.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 25fb144..bf6c406 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -809,7 +809,7 @@ static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4)
 	if (is_udplite)  				 /*     UDP-Lite      */
 		csum = udplite_csum(skb);
 
-	else if (sk->sk_no_check_tx && !skb_is_gso(skb)) {   /* UDP csum off */
+	else if (sk->sk_no_check_tx) {			 /* UDP csum off */
 
 		skb->ip_summed = CHECKSUM_NONE;
 		goto send;