flow_dissector: Use 'const' where possible.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index eabfb81..2738d35 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1029,9 +1029,9 @@
 	return skb->hash;
 }
 
-__u32 __skb_get_hash_flowi6(struct sk_buff *skb, struct flowi6 *fl6);
+__u32 __skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6);
 
-static inline __u32 skb_get_hash_flowi6(struct sk_buff *skb, struct flowi6 *fl6)
+static inline __u32 skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6)
 {
 	if (!skb->l4_hash && !skb->sw_hash) {
 		struct flow_keys keys;
@@ -1043,9 +1043,9 @@
 	return skb->hash;
 }
 
-__u32 __skb_get_hash_flowi4(struct sk_buff *skb, struct flowi4 *fl);
+__u32 __skb_get_hash_flowi4(struct sk_buff *skb, const struct flowi4 *fl);
 
-static inline __u32 skb_get_hash_flowi4(struct sk_buff *skb, struct flowi4 *fl4)
+static inline __u32 skb_get_hash_flowi4(struct sk_buff *skb, const struct flowi4 *fl4)
 {
 	if (!skb->l4_hash && !skb->sw_hash) {
 		struct flow_keys keys;