net: ip_tunnel: remove 'csum_help' argument to iptunnel_handle_offloads

All users now pass false, so we can remove it, and remove the code that
 was conditional upon it.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index 4044da6..6ec5b42 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -219,7 +219,7 @@
 	if (unlikely(skb->protocol != htons(ETH_P_IP)))
 		goto tx_error;
 
-	skb = iptunnel_handle_offloads(skb, false, SKB_GSO_IPIP);
+	skb = iptunnel_handle_offloads(skb, SKB_GSO_IPIP);
 	if (IS_ERR(skb))
 		goto out;