tipc: clean up removal of binding table items

tipc: clean up removal of binding table items

In commit 5ae2591bc8eb ("tipc: fix use-after-free in tipc_nametbl_stop")
we fixed a problem caused by premature release of service range items.

That fix is correct, and solved the problem. However, it doesn't address
the root of the problem, which is that we don't lookup the tipc_service
 -> service_range -> publication items in the correct hierarchical
order.

In this commit we try to make this right, and as a side effect obtain
some code simplification.

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