bnx2x: Fix statistics gathering on link change

Since driver statistics flow access MACs and those might reset during
link re-configurations, when we're about to change link properties we
have to make sure that statistics are not operational.
Statisics would be re-enabled [i.e., gathering of statistics would
re-commence] once physical link is achieved again.

Since driver employs a link-flap avoidance scheme, there are scenarios
where driver will receive no indication that the new link is up, and
as a result the statistics would not be re-enabled.

Preventing LFA from working in such cases would guarantee that we'll
always receive such indications and thus will fix statistics gathering.

Signed-off-by: Ariel Elior <Ariel.Elior@qlogic.com>
Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>