ARM: dts: am43x-epos-evm: Update binding for touchscreen size

Update the bindings for touchscreen size.
Signed-off-by: NRoger Quadros <rogerq@ti.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

arch/arm/boot/dts/am43x-epos-evm.dts

@@ -344,8 +344,8 @@
 
 		attb-gpio = <&gpio1 17 GPIO_ACTIVE_HIGH>;
 
-		x-size = <1024>;
-		y-size = <600>;
+		touchscreen-size-x = <1024>;
+		touchscreen-size-y = <600>;
 	};
 };