[NETFILTER]: Do not copy skb in skb_make_writable

Now that all callers of netfilter can guarantee that the skb is not shared,
we no longer have to copy the skb in skb_make_writable.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
index 1dd075e..2505348c 100644
--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -287,7 +287,7 @@
 /* Call this before modifying an existing packet: ensures it is
    modifiable and linear to the point you care about (writable_len).
    Returns true or false. */
-extern int skb_make_writable(struct sk_buff **pskb, unsigned int writable_len);
+extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);
 
 static inline void nf_csum_replace4(__sum16 *sum, __be32 from, __be32 to)
 {