RDMA/bnxt_re: Add a new uapi for driver notification

Add driver notify uapi for application notifying
the driver about the doorbell FIFO congestion.

Link: https://lore.kernel.org/r/1689742977-9128-8-git-send-email-selvin.xavier@broadcom.com


Signed-off-by: Chandramohan Akula <chandramohan.akula@broadcom.com>
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>