ipv6: remove obsolete inet6 functions

struct dst_entry *inet6_csk_route_req(const struct sock *sk, struct flowi6 *fl6,

				      const struct request_sock *req, u8 proto);

struct request_sock *inet6_csk_search_req(struct sock *sk,

					  const __be16 rport,

					  const struct in6_addr *raddr,

					  const struct in6_addr *laddr,

					  const int iif);

void inet6_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,

				    const unsigned long timeout);

void inet6_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr);

int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl);