lantiq: correct Fritz!Box 7412 button logic level

The AVM FRITZ!Box 7412 buttons are both active low, which is currently
incorrectly defined in the device-tree.

This leads to the device booting directly into failsafe.

Signed-off-by: David Bauer <mail@david-bauer.net>
(cherry picked from commit c12947b39e)

target/linux/lantiq/files-4.14/arch/mips/boot/dts/FRITZ7412.dts

@@ -33,13 +33,13 @@
 		
 		wps {
 			label = "wps";
-			gpios = <&gpio 1 GPIO_ACTIVE_HIGH>;
+			gpios = <&gpio 1 GPIO_ACTIVE_LOW>;
 			linux,code = <KEY_WPS_BUTTON>;
 		};
 		
 		dect {
 			label = "dect";
-			gpios = <&gpio 2 GPIO_ACTIVE_HIGH>;
+			gpios = <&gpio 2 GPIO_ACTIVE_LOW>;
 			linux,code = <KEY_PHONE>;
 		};
 	};