dt-bindings: net: dsa: lantiq: add xRx300 and xRX330 switch bindings

Add compatible string for xRX300 and xRX330 SoCs.
Signed-off-by: Aleksander Jan Bajkowski <olek2@wp.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/dsa/lantiq-gswip.txt

@@ -5,6 +5,10 @@ Required properties for GSWIP core:
 
 - compatible	: "lantiq,xrx200-gswip" for the embedded GSWIP in the
 		  xRX200 SoC
+		  "lantiq,xrx300-gswip" for the embedded GSWIP in the
+		  xRX300 SoC
+		  "lantiq,xrx330-gswip" for the embedded GSWIP in the
+		  xRX330 SoC
 - reg		: memory range of the GSWIP core registers
 		: memory range of the GSWIP MDIO registers
 		: memory range of the GSWIP MII registers