ARM: tegra: Add compatible string for built-in ASIX on Colibri boards

The device tree node for the built-in ASIX Ethernet device on Colibri
boards needs a compatible string in order to pass DT schema validation.
Add the USB VID,PID compatible string as required by the DT schema for
USB devices.
Reviewed-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm/boot/dts/tegra20-colibri.dtsi

@@ -691,6 +691,7 @@ usb@c5004000 {
 		#size-cells = <0>;
 
 		asix@1 {
+			compatible = "usbb95,772b";
 			reg = <1>;
 			local-mac-address = [00 00 00 00 00 00];
 		};

arch/arm/boot/dts/tegra30-colibri.dtsi

@@ -953,6 +953,7 @@ usb@7d004000 {
 		#size-cells = <0>;
 
 		asix@1 {
+			compatible = "usbb95,772b";
 			reg = <1>;
 			local-mac-address = [00 00 00 00 00 00];
 		};