RDMA/hns: fix memory leak in hns_roce_alloc_mr()

When hns_roce_mr_enable() failed in hns_roce_alloc_mr(), mr_key is not
released. Compiled test only.

Fixes: 9b2cf76c ("RDMA/hns: Optimize PBL buffer allocation process")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Link: https://lore.kernel.org/r/20221119070834.48502-1-shaozhengchao@huawei.com


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