A new parameter for the module, mac_addr, as a string
of 6 int's
The user can specify a custom mac address for the
board, and instead of the driver read the mac address
programmed in the card's rom, the driver will read it
from this parameter and load the apropriate register.
Ps.: If there are more than one card on the system, the
drivers will use the same mac for all of them. Any idea?