e100: allow bad MAC address when running with invalid eeprom csum

Seved Torstendahl <seved.torstendahl@netinsight.net> suggested to
let the module parameter for invalid eeprom checksum control the valid
mac address test.

If this bypass happens we should print a different message,
or at least one that is correct, maybe something like below

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>