RDMA/rtrs-clt: Kill xchg_paths

Let's call try_cmpxchg directly for the same purpose.

Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Link: https://lore.kernel.org/r/20220903040252.29397-1-guoqing.jiang@linux.dev


Signed-off-by: Leon Romanovsky <leon@kernel.org>