RDMA/hns: Fix unnecessary port_num transition in HW stats allocation

The num_ports capability of devices should be compared with the
number of port(i.e. the input param "port_num") but not the port
index(i.e. port_num - 1).

Fixes: 5a87279 ("RDMA/hns: Support hns HW stats")
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
Link: https://lore.kernel.org/r/20231017125239.164455-7-huangjunxian6@hisilicon.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>

Author: Junxian Huang

drivers/infiniband/hw/hns/hns_roce_main.c

@@ -547,9 +547,8 @@ static struct rdma_hw_stats *hns_roce_alloc_hw_port_stats(
 				struct ib_device *device, u32 port_num)
 {
 	struct hns_roce_dev *hr_dev = to_hr_dev(device);
-	u32 port = port_num - 1;
 
-	if (port > hr_dev->caps.num_ports) {
+	if (port_num > hr_dev->caps.num_ports) {
 		ibdev_err(device, "invalid port num.\n");
 		return NULL;
 	}