ARM: dts: Add nodes for GPIO keys available on Trats

This patch extends dts file of Samsung Trats board to add support for
available GPIO keys using gpio-keys driver.
Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

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

@@ -65,6 +65,39 @@ serial@13830000 {
 		status = "okay";
 	};
 
+	gpio-keys {
+		compatible = "gpio-keys";
+
+		vol-down-key {
+			gpios = <&gpx2 1 1>;
+			linux,code = <114>;
+			label = "volume down";
+			debounce-interval = <10>;
+		};
+
+		vol-up-key {
+			gpios = <&gpx2 0 1>;
+			linux,code = <115>;
+			label = "volume up";
+			debounce-interval = <10>;
+		};
+
+		power-key {
+			gpios = <&gpx2 7 1>;
+			linux,code = <116>;
+			label = "power";
+			debounce-interval = <10>;
+			gpio-key,wakeup;
+		};
+
+		ok-key {
+			gpios = <&gpx3 5 1>;
+			linux,code = <352>;
+			label = "ok";
+			debounce-interval = <10>;
+		};
+	};
+
 	i2c@138B0000 {
 		samsung,i2c-sda-delay = <100>;
 		samsung,i2c-slave-addr = <0x10>;