[NET] Rename open_request to request_sock

Ok, this one just renames some stuff to have a better namespace and to
dissassociate it from TCP:

struct open_request  -> struct request_sock
tcp_openreq_alloc    -> reqsk_alloc
tcp_openreq_free     -> reqsk_free
tcp_openreq_fastfree -> __reqsk_free

With this most of the infrastructure closely resembles a struct
sock methods subset.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 98acdbf..6fcd6a0 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -201,7 +201,7 @@
 	int			iif;
 };
 
-static inline struct tcp6_request_sock *tcp6_rsk(const struct open_request *sk)
+static inline struct tcp6_request_sock *tcp6_rsk(const struct request_sock *sk)
 {
 	return (struct tcp6_request_sock *)sk;
 }