dmascc: fix incomplete conversion to network_device_ops

drivers/net/hamradio/dmascc.c:587: error: 'struct net_device' has no
member named 'set_mac_address'

Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>