arm64: dts: allwinner: a527: add EMAC0 to Radxa A5E board

On Radxa A5E board, the EMAC0 connect to external Maxio MAE0621A PHY,
which features a 25MHz crystal, and using PH8 pin as PHY reset.

Tested on A5E board with schematic V1.20.

Tested-by: Corentin LABBE <clabbe.montjoie@gmail.com>
Signed-off-by: Yixun Lan <dlan@gentoo.org>
Link: https://patch.msgid.link/20250430-01-sun55i-emac0-v3-4-6fc000bbccbd@gentoo.org
Signed-off-by: Chen-Yu Tsai <wens@csie.org>

Author: dlan17

arch/arm64/boot/dts/allwinner/sun55i-a527-cubie-a5e.dts

@@ -12,6 +12,7 @@
 	compatible = "radxa,cubie-a5e", "allwinner,sun55i-a527";
 
 	aliases {
+		ethernet0 = &emac0;
 		serial0 = &uart0;
 	};
 
@@ -54,6 +55,24 @@
 	status = "okay";
 };
 
+&emac0 {
+	phy-mode = "rgmii-id";
+	phy-handle = <&ext_rgmii_phy>;
+	phy-supply = <&reg_cldo3>;
+
+	allwinner,tx-delay-ps = <300>;
+	allwinner,rx-delay-ps = <400>;
+
+	status = "okay";
+};
+
+&mdio0 {
+	ext_rgmii_phy: ethernet-phy@1 {
+		compatible = "ethernet-phy-ieee802.3-c22";
+		reg = <1>;
+	};
+};
+
 &mmc0 {
 	vmmc-supply = <&reg_cldo3>;
 	cd-gpios = <&pio 5 6 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>; /* PF6 */