ARM: dts: exynos: Remove unnecessary address/size properties in Origen

The children of gpio_keys node do not have reg/ranges properties so remove
address-cells and size-cells properties.  This fixes warnings for
Exynos4210 Origen:

    arch/arm/boot/dts/exynos4210-origen.dtb: Warning (avoid_unnecessary_addr_size):
        /gpio_keys: unnecessary #address-cells/#size-cells without "ranges" or child "reg" property
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

arch/arm/boot/dts/exynos4210-origen.dts

@@ -52,8 +52,6 @@ mmc_reg: regulator@0 {
 
 	gpio_keys {
 		compatible = "gpio-keys";
-		#address-cells = <1>;
-		#size-cells = <0>;
 
 		up {
 			label = "Up";