RDMA/rtrs-srv: Release lock before call into close_sess

RDMA/rtrs-srv: Release lock before call into close_sess

[ Upstream commit 99f0c3807973359bba8f37d9198eea59fe38c32a ]

In this error case, we don't need hold mutex to call close_sess.

Fixes: 9cb837480424 ("RDMA/rtrs: server: main functionality")
Link: https://lore.kernel.org/r/20201217141915.56989-4-jinpu.wang@cloud.ionos.com
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Tested-by: Lutz Pogrell <lutz.pogrell@cloud.ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>