ARM: dts: Use GPIO constants for flags cells in exynos5440 boards

The board DTS are using numeric values instead of the defined GPIO
constanst to express polarity, use them to make the DTS more clear.
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>

arch/arm/boot/dts/exynos5440-ssdk5440.dts

@@ -11,6 +11,7 @@
 
 /dts-v1/;
 #include "exynos5440.dtsi"
+#include <dt-bindings/gpio/gpio.h>
 
 / {
 	model = "SAMSUNG SSDK5440 board based on EXYNOS5440";
@@ -29,12 +30,12 @@ xtal {
 };
 
 &pcie_0 {
-	reset-gpio = <&pin_ctrl 5 0>;
+	reset-gpio = <&pin_ctrl 5 GPIO_ACTIVE_HIGH>;
 	status = "okay";
 };
 
 &pcie_1 {
-	reset-gpio = <&pin_ctrl 22 0>;
+	reset-gpio = <&pin_ctrl 22 GPIO_ACTIVE_HIGH>;
 	status = "okay";
 };