RDMA/qedr: Fix doorbell setting

Change the doorbell setting so that the maximum value between the last and
current value is set. This is to avoid doorbells being lost.

Fixes: a7efd777 ("qedr: Add support for PD,PKEY and CQ verbs")
Link: https://lore.kernel.org/r/20200902165741.8355-3-michal.kalderon@marvell.com


Signed-off-by: Michal Kalderon <michal.kalderon@marvell.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>