tipc: Cosmetic changes to node subscription code

Relocates the code that notifies users of node subscriptions so that
it is adjacent to the rest of the routines that implement TIPC's node
subscription capability. Renames the name table routine that is
invoked by a node subscription to better reflect its purpose and to
be consistent with other, similar name table routines.

These changes are cosmetic in nature, and do not alter the behavior
of TIPC.

Signed-off-by: Allan Stephens <Allan.Stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>