firewire: core: remove obsolete comment

Target-like applications or peer-to-peer-like applications require the
global address handler registration which we have right now, or a per-
card registration.  And node lookup, while it would be nice to have,
would be impossible in the brief time between self-ID-complete event and
completion of firewire-core's topology scanning.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>