bnx2x: don't write dcb/llfc fields in STORM memory

We could get hardware attention during DCB/FCoE traffic without this
fix.

Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>