Implement set_mac_address for mcs7830. This enables me to use it with my
cable modem.
Signed-off-by: NOliver Martin <oliver.martin@student.tuwien.ac.at>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>