arm64: allwinner: bananapi-m64: Enable dwmac-sun8i

The dwmac-sun8i  hardware is present on the BananaPi M64.
It uses an external PHY rtl8211e via RGMII.
Signed-off-by: NCorentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

arch/arm64/boot/dts/allwinner/sun50i-a64-bananapi-m64.dts

@@ -67,6 +67,14 @@
 	};
 };
 
+&emac {
+	pinctrl-names = "default";
+	pinctrl-0 = <&rgmii_pins>;
+	phy-mode = "rgmii";
+	phy-handle = <&ext_rgmii_phy>;
+	status = "okay";
+};
+
 &i2c1 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&i2c1_pins>;
@@ -77,6 +85,13 @@
 	bias-pull-up;
 };
 
+&mdio {
+	ext_rgmii_phy: ethernet-phy@1 {
+		compatible = "ethernet-phy-ieee802.3-c22";
+		reg = <1>;
+	};
+};
+
 &mmc0 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&mmc0_pins>;