[IPV4]: Change ip_defrag to return an integer

Now that ip_frag always returns the packet given to it on input, we can
change it to return an integer indicating error instead.  This patch does
that and updates all its callers accordingly.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip.h b/include/net/ip.h
index 3af3ed9..875c5ed 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -332,7 +332,7 @@
 	IP_DEFRAG_VS_FWD
 };
 
-struct sk_buff *ip_defrag(struct sk_buff *skb, u32 user);
+int ip_defrag(struct sk_buff *skb, u32 user);
 extern int ip_frag_nqueues;
 extern atomic_t ip_frag_mem;