ARM: dts: imx51-babbage: Use predefined constants for keys definition

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
diff --git a/arch/arm/boot/dts/imx51-babbage.dts b/arch/arm/boot/dts/imx51-babbage.dts
index 1652f6a..a8d6168 100644
--- a/arch/arm/boot/dts/imx51-babbage.dts
+++ b/arch/arm/boot/dts/imx51-babbage.dts
@@ -88,7 +88,7 @@
 		power {
 			label = "Power Button";
 			gpios = <&gpio2 21 GPIO_ACTIVE_HIGH>;
-			linux,code = <116>; /* KEY_POWER */
+			linux,code = <KEY_POWER>;
 			gpio-key,wakeup;
 		};
 	};