ARM: dts: Fix apparent GPIO typo in exynos5250-arndale

The GPIO flag 2 has no constant assigned, so this was probably
active-low.
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Andreas Faerber <afaerber@suse.de>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/boot/dts/exynos5250-arndale.dts

@@ -155,7 +155,7 @@ timing0: timing@0 {
 };
 
 &hdmi {
-	hpd-gpio = <&gpx3 7 2>;
+	hpd-gpio = <&gpx3 7 GPIO_ACTIVE_LOW>;
 	vdd_osc-supply = <&ldo10_reg>;
 	vdd_pll-supply = <&ldo8_reg>;
 	vdd-supply = <&ldo8_reg>;