[INET]: Consolidate xxx_frag_intern

This routine checks for the existence of a given entry
in the hash table and inserts the new one if needed.

The ->equal callback is used to compare two frag_queue-s
together, but this one is temporary and will be removed
later. The netfilter code and the ipv6 one use the same
routine to compare frags.

The inet_frag_intern() always returns non-NULL pointer,
so convert the inet_frag_queue into protocol specific
one (with the container_of) without any checks.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index cc796cb..ff12697 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -377,6 +377,9 @@
 				   prefixlen);
 }
 
+struct inet_frag_queue;
+int ip6_frag_equal(struct inet_frag_queue *q1, struct inet_frag_queue *q2);
+
 static inline int ipv6_addr_any(const struct in6_addr *a)
 {
 	return ((a->s6_addr32[0] | a->s6_addr32[1] |