ARM: dts: imx28-evk: add heartbeat gpio-leds

Add heartbeat gpio-leds for imx28-evk board.
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx28-evk.dts

@@ -169,4 +169,14 @@
 		saif-controllers = <&saif0 &saif1>;
 		audio-codec = <&sgtl5000>;
 	};
+
+	leds {
+		compatible = "gpio-leds";
+
+		user {
+			label = "Heartbeat";
+			gpios = <&gpio3 5 0>;
+			linux,default-trigger = "heartbeat";
+		};
+	};
 };