net: remove comment in ndisc_router_discovery

Removes superfluous (and misplaced) comment from ndisc_router_discovery.

Signed-off-by: Patrick Rohr <prohr@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20230726184742.342825-1-prohr@google.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>