RDMA/rtrs-clt: Fix one kernel-doc comment

RDMA/rtrs-clt: Fix one kernel-doc comment

Add the description of @pathname and remove @sessname in rtrs_clt_open()
kernel-doc comment to remove warnings found by running scripts/kernel-doc,
which is caused by using 'make W=1'.

drivers/infiniband/ulp/rtrs/rtrs-clt.c:2809: warning: Function parameter or member 'pathname' not described in 'rtrs_clt_open'
drivers/infiniband/ulp/rtrs/rtrs-clt.c:2809: warning: Excess function parameter 'sessname' description in 'rtrs_clt_open'

Link: https://lore.kernel.org/r/20220526130945.98601-1-yang.lee@linux.alibaba.com
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reviewed-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>