tipc: merge struct tipc_port into struct tipc_sock

We complete the merging of the port and socket layer by aggregating
the fields of struct tipc_port directly into struct tipc_sock, and
moving the combined structure into socket.c.

We also move all functions and macros that are not any longer
exposed to the rest of the stack into socket.c, and rename them
accordingly.

Despite the size of this commit, there are no functional changes.
We have only made such changes that are necessary due of the removal
of struct tipc_port.

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