ARM: dts: remove unnecessary gpio-key nodes for exynos3250 boards

This patch removes unnecessary property of gpio-keys node. The
gpio-keys driver doesn't use interrupts and interrupt-parent.

Cc: Youngjun Cho <yj44.cho@samsung.com>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: NChanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: NBeomho Seo <beomho.seo@samsung.com>
Signed-off-by: NKukjin Kim <kgene@kernel.org>

arch/arm/boot/dts/exynos3250-monk.dts

@@ -37,8 +37,6 @@
 		compatible = "gpio-keys";
 
 		power_key {
-			interrupt-parent = <&gpx2>;
-			interrupts = <7 0>;
 			gpios = <&gpx2 7 1>;
 			linux,code = <KEY_POWER>;
 			label = "power key";

arch/arm/boot/dts/exynos3250-rinato.dts

@@ -37,8 +37,6 @@
 		compatible = "gpio-keys";
 
 		power_key {
-			interrupt-parent = <&gpx2>;
-			interrupts = <7 0>;
 			gpios = <&gpx2 7 1>;
 			linux,code = <KEY_POWER>;
 			label = "power key";