tipc: aggregate port structure into socket structure

After the removal of the tipc native API the relation between
a tipc_port and its API types is strictly one-to-one, i.e, the
latter can now only be a socket API. There is therefore no need
to allocate struct tipc_port and struct sock independently.

In this commit, we aggregate struct tipc_port into struct tipc_sock,
hence saving both CPU cycles and structure complexity.

There are no functional changes in this commit, except for the
elimination of the separate allocation/freeing of tipc_port.
All other changes are just adaptatons to the new data structure.

This commit also opens up for further code simplifications and
code volume reduction, something we will do in later commits.

Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>