net: m68k/nfeth: Remove wrong usage of dev->flags

Remove wrong setting of dev->flags. NETIF_F_NO_CSUM maps to IFF_DEBUG
there, so looks like a mistake.

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