riscv: dts: sophgo: Enable ethernet device for Huashan Pi

Enable ethernet controller and mdio multiplexer device on Huashan Pi.

Link: https://lore.kernel.org/r/20250703021600.125550-4-inochiama@gmail.com
Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
Signed-off-by: Chen Wang <wangchen20@iscas.ac.cn>

Author: inochisa

arch/riscv/boot/dts/sophgo/cv1812h-huashan-pi.dts

@@ -55,6 +55,14 @@
 	non-removable;
 };
 
+&gmac0 {
+	status = "okay";
+};
+
+&mdio {
+	status = "okay";
+};
+
 &sdhci0 {
 	status = "okay";
 	bus-width = <4>;