sctp: remove the NETIF_F_SG flag before calling skb_segment

It makes more sense to clear NETIF_F_SG instead of set it when
calling skb_segment() in sctp_gso_segment(), since SCTP GSO is
using head_skb's fraglist, of which all frags are linear skbs.

This will make SCTP GSO code more understandable.
Suggested-by: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/sctp/offload.c

@@ -68,7 +68,7 @@ static struct sk_buff *sctp_gso_segment(struct sk_buff *skb,
 		goto out;
 	}
 
-	segs = skb_segment(skb, features | NETIF_F_HW_CSUM | NETIF_F_SG);
+	segs = skb_segment(skb, (features | NETIF_F_HW_CSUM) & ~NETIF_F_SG);
 	if (IS_ERR(segs))
 		goto out;