bnx2x: Test nvram when interface is down

Since commit 3fb43eb ("bnx2x: Change to D3hot only on removal") nvram
is accessible whenever the driver is loaded - Thus it is possible to
test it during self-test even if the interface is down

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>