net: remove skb_frag_add_head

It's not used anywhere.
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -2678,12 +2678,6 @@ static inline void skb_frag_list_init(struct sk_buff *skb)
 	skb_shinfo(skb)->frag_list = NULL;
 }
 
-static inline void skb_frag_add_head(struct sk_buff *skb, struct sk_buff *frag)
-{
-	frag->next = skb_shinfo(skb)->frag_list;
-	skb_shinfo(skb)->frag_list = frag;
-}
-
 #define skb_walk_frags(skb, iter)	\
 	for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)