arm64: dts: allwinner: a64: a64-olinuxino: set the PHY TX delay

The PHY found on the A64-OLinuXino requires a TX delay in order to
operate properly. Olimex uses a 600ps second delay in their BSP, and
that has been found to work, so let's use that value in the current
DT.
Signed-off-by: Rodrigo Exterckötter Tjäder <rodrigo@tjader.xyz>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>

arch/arm64/boot/dts/allwinner/sun50i-a64-olinuxino.dts

@@ -105,6 +105,7 @@ &emac {
 	phy-mode = "rgmii";
 	phy-handle = <&ext_rgmii_phy>;
 	phy-supply = <&reg_dcdc1>;
+	allwinner,tx-delay-ps = <600>;
 	status = "okay";
 };