RDMA/rtrs: Cleanup the code in rtrs_srv_rdma_cm_handler

Let these cases share the same path since all of them need to close
session.

Link: https://lore.kernel.org/r/20210325153308.1214057-11-gi-oh.kim@ionos.com


Signed-off-by: Guoqing Jiang <guoqing.jiang@ionos.com>
Reviewed-by: Danil Kipnis <danil.kipnis@ionos.com>
Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>