tipc: rename struct subscription to struct tipc_subscription

Make this rename so that it is consistent with the majority
of the other tipc structs and to assist in removing any
ambiguity with other similar names in other subsystems.

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

diff --cc net/tipc/name_table.c
Simple merge

diff --cc net/tipc/name_table.h
Simple merge

diff --cc net/tipc/subscr.c
Simple merge

diff --cc net/tipc/subscr.h
Simple merge