tipc: Use genl_register_family_with_ops()

Use genl_register_family_with_ops() instead of a copy. This also changes
netlink related variable names to be kernel-wide unique for consistency
with other users.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>