net: hns3: do not initialize MDIO bus when PHY is inexistent

For some cases, PHY may not be connected to MDIO bus, then
the driver will initialize fail since MDIO bus initialization
fails.

This patch fixes it by skipping the MDIO bus initialization
when PHY is inexistent.
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_mdio.c

@@ -121,12 +121,18 @@ static int hclge_mdio_read(struct mii_bus *bus, int phyid, int regnum)
 
 int hclge_mac_mdio_config(struct hclge_dev *hdev)
 {
+#define PHY_INEXISTENT	255
+
 	struct hclge_mac *mac = &hdev->hw.mac;
 	struct phy_device *phydev;
 	struct mii_bus *mdio_bus;
 	int ret;
 
-	if (hdev->hw.mac.phy_addr >= PHY_MAX_ADDR) {
+	if (hdev->hw.mac.phy_addr == PHY_INEXISTENT) {
+		dev_info(&hdev->pdev->dev,
+			 "no phy device is connected to mdio bus\n");
+		return 0;
+	} else if (hdev->hw.mac.phy_addr >= PHY_MAX_ADDR) {
 		dev_err(&hdev->pdev->dev, "phy_addr(%d) is too large.\n",
 			hdev->hw.mac.phy_addr);
 		return -EINVAL;