arm64: tegra: Set the correct PHY mode for MGBE

The PHY is configured in 10GBASE-R, so make sure to reflect that in DT.

Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Author: thierryreding

arch/arm64/boot/dts/nvidia/tegra234-p3737-0000+p3701-0000.dts

@@ -175,7 +175,7 @@
 			status = "okay";
 
 			phy-handle = <&mgbe0_phy>;
-			phy-mode = "usxgmii";
+			phy-mode = "10gbase-r";
 
 			mdio {
 				#address-cells = <1>;