bnx2x: update fairness parameters following DCB negotiation

ETS can be enabled as a result of DCB negotiation, then
fairness must be recalculated after each negotiation.

Signed-off-by: Dmitry Kravkov <dmitry@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>