ath79: huawei,ap6010dn: fix PHY unit address

The PHY node is named ethernet-phy@18 while its reg is 0x4. Rename
it to ethernet-phy@4 so the unit address matches the reg, as the
AR8035 is strapped to MDIO address 4.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/25801
Signed-off-by: Robert Marko <robimarko@gmail.com>

target/linux/ath79/dts/ar9344_huawei_ap6010dn.dts

@@ -227,7 +227,7 @@
 &mdio0 {
 	status = "okay";
 
-	phy: ethernet-phy@18 {
+	phy: ethernet-phy@4 {
 		reg = <0x4>;
 	};
 };