[IPCOMP]: Fix reception of incompressible packets

I made a silly typo by entering IPPROTO_IP (== 0) instead of
IPPROTO_IPIP (== 4).  This broke the reception of incompressible
packets.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/xfrm4_tunnel.c b/net/ipv4/xfrm4_tunnel.c
index 87f77e4..41f5982 100644
--- a/net/ipv4/xfrm4_tunnel.c
+++ b/net/ipv4/xfrm4_tunnel.c
@@ -50,7 +50,7 @@
 
 static int xfrm_tunnel_rcv(struct sk_buff *skb)
 {
-	return xfrm4_rcv_spi(skb, IPPROTO_IP, ip_hdr(skb)->saddr);
+	return xfrm4_rcv_spi(skb, IPPROTO_IPIP, ip_hdr(skb)->saddr);
 }
 
 static int xfrm_tunnel_err(struct sk_buff *skb, u32 info)