net: sfc: use skb_list_walk_safe helper for gso segments

This is a straight-forward conversion case for the new function, and
while we're at it, we can remove a null write to skb->next by replacing
it with skb_mark_not_on_list.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/tx.c

@@ -307,12 +307,9 @@ static int efx_tx_tso_fallback(struct efx_tx_queue *tx_queue,
 	dev_consume_skb_any(skb);
 	skb = segments;
 
-	while (skb) {
-		next = skb->next;
-		skb->next = NULL;
-
+	skb_list_walk_safe(skb, skb, next) {
+		skb_mark_not_on_list(skb);
 		efx_enqueue_skb(tx_queue, skb);
-		skb = next;
 	}
 
 	return 0;