arm64: dts: allwinner: h6: orangepi-one-plus: Fix ethernet

RX/TX delay on OrangePi One Plus board is set on PHY. Reflect that in
ethernet node.

Fixes: 7ee32a17 ("arm64: dts: allwinner: h6: orangepi-one-plus: Enable ethernet")
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Marcus Cooper <codekipper@gmail.com>
Link: https://lore.kernel.org/r/20201101072609.1681891-1-jernej.skrabec@siol.net

arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-one-plus.dts

@@ -27,7 +27,7 @@ reg_gmac_3v3: gmac-3v3 {
 &emac {
 	pinctrl-names = "default";
 	pinctrl-0 = <&ext_rgmii_pins>;
-	phy-mode = "rgmii";
+	phy-mode = "rgmii-id";
 	phy-handle = <&ext_rgmii_phy>;
 	phy-supply = <&reg_gmac_3v3>;
 	allwinner,rx-delay-ps = <200>;