ARM: dts: ethernut5: Fix the build warning

Fix the building warning as below:
---8<----
Warning (reg_format): "reg" property in /i2c-gpio-0/pcf8563@50 has invalid length (4 bytes) (#address-cells == 2, #size-cells == 1)
Warning (avoid_default_addr_size): Relying on default #address-cells value for /i2c-gpio-0/pcf8563@50
Warning (avoid_default_addr_size): Relying on default #size-cells value for /i2c-gpio-0/pcf8563@50
--->8----

Signed-off-by: Wenyou Yang <wenyou.yang@microchip.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

arch/arm/dts/ethernut5.dts

@@ -84,6 +84,8 @@
 	};
 
 	i2c-gpio-0 {
+		#address-cells = <1>;
+		#size-cells = <0>;
 		status = "okay";
 
 		pcf8563@50 {