RDMA/rtrs-clt: Remove redundant code from rtrs_clt_read_req

RDMA/rtrs-clt: Remove redundant code from rtrs_clt_read_req

There is no need to dereference 's' from 'sess', since we have "sess =
to_clt_sess(s)" before.

And we can deference 'dev' from 's' earlier.

Link: https://lore.kernel.org/r/20210325153308.1214057-8-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>