ARM: dts: fix pinctrl for s2mps11-irq on exynos5420-arndale-octa

On Arndale Octa the S2MPS11 RTC alarm interrupt was not handled
at all because of wrong configuration of interrupt and gpx3-2.
1. Interrupt is signaled by falling edge.
2. This GPIO line is hard-wired on the board to PVDD_APIO_1V8
   through a resistor so pull-up/down must be disabled.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>

arch/arm/boot/dts/exynos5420-arndale-octa.dts

@@ -90,7 +90,9 @@ s2mps11_pmic@66 {
 			s2mps11,buck4-ramp-enable = <1>;
 
 			interrupt-parent = <&gpx3>;
-			interrupts = <2 IRQ_TYPE_LEVEL_HIGH>;
+			interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
+			pinctrl-names = "default";
+			pinctrl-0 = <&s2mps11_irq>;
 
 			s2mps11_osc: clocks {
 				#clock-cells = <1>;
@@ -376,3 +378,12 @@ &usbdrd_dwc3_1 {
 &cci {
 	status = "disabled";
 };
+
+&pinctrl_0 {
+	s2mps11_irq: s2mps11-irq {
+		samsung,pins = "gpx3-2";
+		samsung,pin-function = <0xf>;
+		samsung,pin-pud = <0>;
+		samsung,pin-drv = <0>;
+	};
+};