tipc: re-organize members of struct publication

In a future commit we will introduce more members to struct publication.
In order to keep this structure comprehensible we now group some of
its current fields into the sub-structures where they really belong,
- A struct tipc_service_range for the functional address the publication
  is representing.
- A struct tipc_socket_addr for the socket bound to that service range.

We also rename the stack variable 'publ' to just 'p' in a few places.
This is just as easy to understand in the given context, and keeps the
number of wrapped code lines to a minimum.

There are no functional changes in this 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>