qed: Expose the doorbell overflow recovery mechanism to the protocol drivers

Most of the doorbelling entities are outside of the core module.
L2 queues, Roce queues, iscsi and fcoe all need to register.
Make the APIs available for these drivers.

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>