ARM: at91: change compatibility string for sama5d3x gem

this new compatibility string prevents macb/gem driver from using the
scatter-gather and gso features on sama5d3x boards.
Signed-off-by: NCyrille Pitchen <cyrille.pitchen@atmel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

arch/arm/boot/dts/sama5d3_gmac.dtsi

@@ -74,7 +74,7 @@
 			};
 
 			macb0: ethernet@f0028000 {
-				compatible = "cdns,pc302-gem", "cdns,gem";
+				compatible = "atmel,sama5d3-gem";
 				reg = <0xf0028000 0x100>;
 				interrupts = <34 IRQ_TYPE_LEVEL_HIGH 3>;
 				pinctrl-names = "default";