qed: Fix possible race when reading firmware return code.

qed: Fix possible race when reading firmware return code.

Orabug: 25477939

While handling SPQ ramrod completion, there is a possible race
where driver might not read updated fw return code based on
ramrod completion done. This patch ensures that fw return code
is written first and then completion done flag is updated
using appropriate memory barriers.

Signed-off-by: Manish Chopra <manish.chopra@caviumnetworks.com>
Signed-off-by: Yuval Mintz <Yuval.Mintz@caviumnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit d5df7688b6a36dbb5611a58229a5e294cd978999)
Signed-off-by: Brian Maly <brian.maly@oracle.com>