RDMA/hns: Remove unnecessary checks for NULL in mtr_alloc_bufs()

ib_umem_get() never return NULL.

Fixes: 3c873161 ("RDMA/hns: Add support for addressing when hopnum is 0")
Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
Link: https://lore.kernel.org/r/20231207114231.2872104-5-huangjunxian6@hisilicon.comSigned-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/hw/hns/hns_roce_mr.c

@@ -686,7 +686,7 @@ static int mtr_alloc_bufs(struct hns_roce_dev *hr_dev, struct hns_roce_mtr *mtr,
 		mtr->kmem = NULL;
 		mtr->umem = ib_umem_get(ibdev, user_addr, total_size,
 					buf_attr->user_access);
-		if (IS_ERR_OR_NULL(mtr->umem)) {
+		if (IS_ERR(mtr->umem)) {
 			ibdev_err(ibdev, "failed to get umem, ret = %ld.\n",
 				  PTR_ERR(mtr->umem));
 			return -ENOMEM;