net: hns: Use IS_ERR_OR_NULL() helper function

Use the IS_ERR_OR_NULL() helper instead of open-coding a
NULL and an error pointer checks to simplify the code and
improve readability.
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20240828122336.3697176-1-lihongbo22@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/hisilicon/hns/hns_dsaf_mac.c

@@ -734,7 +734,7 @@ hns_mac_register_phydev(struct mii_bus *mdio, struct hns_mac_cb *mac_cb,
 		return -ENODATA;
 
 	phy = get_phy_device(mdio, addr, is_c45);
-	if (!phy || IS_ERR(phy))
+	if (IS_ERR_OR_NULL(phy))
 		return -EIO;
 
 	phy->irq = mdio->irq[addr];