lantiq/xrx200: make WLAN button responsive on Fritzbox 3370

Pressing the 'WLAN' button should enable/disable wireless activity.
However, on the Fritzbox 3370 this doesn't have an effect.
This patch changes the mapping of the physical WLAN button, so a button
press will emit an action for the 'rfkill' key instead of 'wlan'.
Apparently, this is what stock OpenWRT expects, and also what is
implemented for most other devices.

Signed-off-by: Dustin Gathmann <dzsoftware@posteo.org>

target/linux/lantiq/files-4.19/arch/mips/boot/dts/lantiq/vr9_avm_fritz3370-rev2.dtsi

@@ -45,7 +45,7 @@
 		wifi {
 			label = "wlan";
 			gpios = <&gpio 29 GPIO_ACTIVE_HIGH>;
-			linux,code = <KEY_WLAN>;
+			linux,code = <KEY_RFKILL>;
 		};
 	};
 

target/linux/lantiq/files-5.4/arch/mips/boot/dts/lantiq/vr9_avm_fritz3370-rev2.dtsi

@@ -45,7 +45,7 @@
 		wifi {
 			label = "wlan";
 			gpios = <&gpio 29 GPIO_ACTIVE_HIGH>;
-			linux,code = <KEY_WLAN>;
+			linux,code = <KEY_RFKILL>;
 		};
 	};