ARM: dts: exynos: add function to LED nodes in Tiny4412

Add common LED property - the function - to LED nodes in Tiny4412.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220620175716.132143-3-krzysztof.kozlowski@linaro.org

arch/arm/boot/dts/exynos4412-tiny4412.dts

@@ -11,6 +11,7 @@
 /dts-v1/;
 #include "exynos4412.dtsi"
 #include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/leds/common.h>
 
 / {
 	model = "FriendlyARM TINY4412 board based on Exynos4412";
@@ -30,6 +31,7 @@ leds {
 
 		led1 {
 			label = "led1";
+			function = LED_FUNCTION_HEARTBEAT;
 			gpios = <&gpm4 0 GPIO_ACTIVE_LOW>;
 			default-state = "off";
 			linux,default-trigger = "heartbeat";
@@ -49,6 +51,7 @@ led3 {
 
 		led4 {
 			label = "led4";
+			function = LED_FUNCTION_DISK_ACTIVITY;
 			gpios = <&gpm4 3 GPIO_ACTIVE_LOW>;
 			default-state = "off";
 			linux,default-trigger = "mmc0";