RDMA/nes: Adding queue drain functions

Adding sq and rq drain functions, which block until all
previously posted wr-s in the specified queue have completed.
A completion object is signaled to unblock the thread,
when the last cqe for the corresponding queue is processed.

Signed-off-by: Tatyana Nikolova <tatyana.e.nikolova@intel.com>
Signed-off-by: Faisal Latif <faisal.latif@intel.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/nes/nes_verbs.h

@@ -189,6 +189,8 @@ struct nes_qp {
 	u8                    pau_pending;
 	u8                    pau_state;
 	__u64                 nesuqp_addr;
+	struct completion     sq_drained;
+	struct completion     rq_drained;
 };
 
 struct ib_mr *nes_reg_phys_mr(struct ib_pd *ib_pd,