qed: Register light L2 queues with doorbell overflow recovery mechanism

Light L2 queues are doorbelling entities. Modify the implementation
to keep the doorbell data necessary for doorbelling in well known
location instead of recomputing every time. Register the LL2 queue
with doorbell recovery mechanism.

Signed-off-by: Ariel Elior <Ariel.Elior@cavium.com>
Signed-off-by: Michal Kalderon <Michal.Kalderon@cavium.com>
Signed-off-by: Tomer Tayar <Tomer.Tayar@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>