To avoid leakage for QPs assocoated with SRQ, according to IB spec
(section 10.3.1):

"Note, for QPs that are associated with an SRQ, the Consumer should take
the QP through the Error State before invoking a Destroy QP or a Modify
QP to the Reset State. The Consumer may invoke the Destroy QP without
first performing a Modify QP to the Error State and waiting for the Affiliated
Asynchronous Last WQE Reached Event. However, if the Consumer
does not wait for the Affiliated Asynchronous Last WQE Reached Event,
then WQE and Data Segment leakage may occur. Therefore, it is good
programming practice to teardown a QP that is associated with an SRQ
by using the following process:
 - Put the QP in the Error State;
 - wait for the Affiliated Asynchronous Last WQE Reached Event;
 - either:
   - drain the CQ by invoking the Poll CQ verb and either wait for CQ
     to be empty or the number of Poll CQ operations has exceeded
     CQ capacity size; or
   - post another WR that completes on the same CQ and wait for this
     WR to return as a WC;
 - and then invoke a Destroy QP or Reset QP."

Catch the Last WQE Reached Event in the core layer during drain QP flow.
Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Link: https://lore.kernel.org/r/20240619171153.34631-2-mgurtovoy@nvidia.comReviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>