qed: Set the doorbell address correctly

In 100g mode the doorbell bar is united for both engines. Set
the correct offset in the hwfn so that the doorbell returned
for RoCE is in the affined hwfn.

Signed-off-by: Ariel Elior <ariel.elior@marvell.com>
Signed-off-by: Denis Bolotin <denis.bolotin@marvell.com>
Signed-off-by: Michal Kalderon <michal.kalderon@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>