tipc: move creation of publication item one level up in call chain

We instantiate struct publication in tipc_nametbl_insert_publ()
instead of as currently in tipc_service_insert_publ(). This has the
advantage that we can pass a pointer to the publication struct to
the next call levels, instead of the numerous individual parameters
we pass on now. It also gives us a location to keep the contents of
the additional fields we will introduce in a later commit.

Signed-off-by: Jon Maloy <jmaloy@redhat.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Acked-by: Hoang Le <hoang.h.le@dektech.com.au>
Acked-by: Tung Nguyen <tung.q.nguyen@dektech.com.au>
Acked-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>