Unfortunately its easy to trigger such error messages by removing the
cable while sending streams of data over the link.

Such errors are normal, and therefore this patch stops firewire-net from
flooding the kernel log with these errors, by combining series of same
errors together.
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>

(Stefan R:)  Eventually we should remove this logging when firewire-net
and related firewire-ohci facilities have been stabilized.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>