bnx2x: Added nvram personalities support

When a device is configured to act as either iscsi or fcoe
device in its nvram, prevent the other from being misused by
preventing its activation in the driver.

Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>