forcedeth: mac address correct

In older chipsets, the mac address was stored in reversed order.
However, in newer chipsets, the mac address is in correct order. This
patch takes those newer chipsets into account and does not rely on a
special bit setup by BIOS'.

Signed-Off-By: Ayaz Abdulla <aabdulla@nvidia.com>

Signed-off-by: Jeff Garzik <jeff@garzik.org>