boards: frdm_k22f: replace legacy devicetree active flags

Replace the legacy flags that assumed active level was relevant
only to input signals with the generic active level flags used
in Linux.

Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
diff --git a/boards/arm/frdm_k22f/frdm_k22f.dts b/boards/arm/frdm_k22f/frdm_k22f.dts
index f44f49e..4e4003a 100644
--- a/boards/arm/frdm_k22f/frdm_k22f.dts
+++ b/boards/arm/frdm_k22f/frdm_k22f.dts
@@ -49,11 +49,11 @@
 		compatible = "gpio-keys";
 		user_button_2: button_0 {
 			label = "User SW2";
-			gpios = <&gpioc 1 GPIO_INT_ACTIVE_LOW>;
+			gpios = <&gpioc 1 GPIO_ACTIVE_LOW>;
 		};
 		user_button_3: button_1 {
 			label = "User SW3";
-			gpios = <&gpiob 17 GPIO_INT_ACTIVE_LOW>;
+			gpios = <&gpiob 17 GPIO_ACTIVE_LOW>;
 		};
 	};