tipc: Correct misnamed references to neighbor discovery domain

Renames items that are improperly labelled as "network scope" items
(which are represented by simple integer values) rather than "network
domain" items (which are represented by <Z.C.N>-type network addresses).
This change is purely cosmetic, and does not affect the operation of TIPC.

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