bnx2x: downgrade "valid ME register value" message level

"valid ME register value" is not an error. It should be logged for
debugging only.

Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Acked-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>