RDMA/hns: Fix refcount leak in hns_roce_mmap

rdma_user_mmap_entry_get_pgoff() takes the reference.
Add missing rdma_user_mmap_entry_put() to release the reference.

Fixes: 0045e0d3 ("RDMA/hns: Support direct wqe of userspace")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Acked-by Haoyue Xu <xuhaoyue1@hisilicon.com>
Link: https://lore.kernel.org/r/20221223072900.802728-1-linmq006@gmail.com


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