atm: [br2684] allow routed mode operation again

BugLink: http://bugs.launchpad.net/bugs/823296

commit 2e302ebf

 upstream.

in routed mode, we don't have a hardware address so netdev_ops doesnt
need to validate our hardware address via .ndo_validate_addr

Reported-by: Manuel Fuentes <mfuentes@agenciaefe.com>
Signed-off-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Pascal Hambourg <pascal@plouf.fr.eu.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>