ARM: dts: exynos: correct PMIC interrupt trigger level on Odroid XU3 family

The Samsung PMIC datasheets describe the interrupt line as active low
with a requirement of acknowledge from the CPU.  The falling edge
interrupt will mostly work but it's not correct.

Fixes: aac4e061 ("ARM: dts: odroidxu3: Enable wake alarm of S2MPS11 RTC")
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20201210212903.216728-6-krzk@kernel.org

arch/arm/boot/dts/exynos5422-odroid-core.dtsi

@@ -509,7 +509,7 @@ pmic@66 {
 		samsung,s2mps11-acokb-ground;
 
 		interrupt-parent = <&gpx0>;
-		interrupts = <4 IRQ_TYPE_EDGE_FALLING>;
+		interrupts = <4 IRQ_TYPE_LEVEL_LOW>;
 		pinctrl-names = "default";
 		pinctrl-0 = <&s2mps11_irq>;