riscv: dts: starfive: beaglev-starlight: Setup phy reset gpio

The BeagleV Starlight SBC uses a Microchip KSZ9031RNXCA PHY supporting
RGMII-ID which doesn't require any particular setup, other than defining
a reset gpio, as opposed to VisionFive V1 for which the RX internal
delay had to be adjusted.
Co-developed-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>

arch/riscv/boot/dts/starfive/jh7100-beaglev-starlight.dts

@@ -11,3 +11,14 @@ / {
 	model = "BeagleV Starlight Beta";
 	compatible = "beagle,beaglev-starlight-jh7100-r0", "starfive,jh7100";
 };
+
+&gmac {
+	phy-handle = <&phy>;
+};
+
+&mdio {
+	phy: ethernet-phy@7 {
+		reg = <7>;
+		reset-gpios = <&gpio 63 GPIO_ACTIVE_LOW>;
+	};
+};