RDMA/rtrs-srv: Fix missing wr_cqe

We had a few places wr_cqe is not set, which could lead to NULL pointer
deref or GPF in error case.

Fixes: 9cb83748 ("RDMA/rtrs: server: main functionality")
Link: https://lore.kernel.org/r/20201217141915.56989-14-jinpu.wang@cloud.ionos.com


Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Reviewed-by: Md Haris Iqbal <haris.iqbal@cloud.ionos.com>
Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>