tipc: remove source file port.c

In this commit, we move the remaining functions in port.c to
socket.c, and give them new names that correspond to their new
location. We then remove the file port.c.

There are only cosmetic changes to the moved functions.

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>