tipc: fix memory leak during module removal

When the TIPC module is removed, the tasklet handler is disabled
before all other subsystems. This will cause lingering publications
in the name table because the node_down tasklets responsible to
clean up publications from an unreachable node will never run.
When the name table is shut down, these publications are detected
and an error message is logged:
tipc: nametbl_stop(): orphaned hash chain detected
This is actually a memory leak, introduced with commit
993b858e ("tipc: correct the order
of stopping services at rmmod")

Instead of just logging an error and leaking memory, we free
the orphaned entries during nametable shutdown.

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