net: udp: remove redundant initialization in udp_gro_complete

The initialization for 'err' with '-ENOSYS' is redundant and
can be removed, as it is updated soon and not used.

Changes since v1:
- Move the err declaration below struct sock *sk
Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
Link: https://lore.kernel.org/r/5faa01d5.1c69fb81.8451c.cb5b@mx.google.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv4/udp_offload.c

@@ -554,8 +554,8 @@ int udp_gro_complete(struct sk_buff *skb, int nhoff,
 {
 	__be16 newlen = htons(skb->len - nhoff);
 	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
-	int err = -ENOSYS;
 	struct sock *sk;
+	int err;
 
 	uh->len = newlen;