3com/typhoon: reuse eth_mac_addr()

Use eth_mac_addr() for .ndo_set_mac_address, remove
typhoon_set_mac_address() since it do currently the same as
eth_mac_addr(). Additional advantage: eth_mac_addr() already
checks if the given address is valid.

Signed-off-by: Danny Kukawka <danny.kukawka@bisect.de>
Acked-by: Dave Dillow <dave@thedillows.org>
Signed-off-by: David S. Miller <davem@davemloft.net>