ath79: fix button labels for WZR-HP-AG300H and WZR-600DHP

These were present in ar71xx but overlooked when porting to ath79.

Fixes: 480bf28 ("ath79: add support for Buffalo WZR-HP-AG300H")

Signed-off-by: Jeffery To <jeffery.to@gmail.com>

target/linux/ath79/dts/ar7161_buffalo_wzr-hp-ag300h.dtsi

@@ -75,38 +75,44 @@
 		compatible = "gpio-keys";
 
 		reset {
+			label = "reset";
 			linux,code = <KEY_RESTART>;
 			gpios = <&gpio 11 GPIO_ACTIVE_LOW>;
 			debounce-interval = <60>;
 		};
 
 		usb {
+			label = "usb";
 			linux,code = <BTN_2>;
 			gpios = <&gpio 3 GPIO_ACTIVE_LOW>;
 			debounce-interval = <60>;
 		};
 
 		aoss {
+			label = "aoss";
 			linux,code = <KEY_WPS_BUTTON>;
 			gpios = <&gpio 5 GPIO_ACTIVE_LOW>;
 			debounce-interval = <60>;
 		};
 
 		router_auto {
+			label = "router_auto";
 			linux,code = <BTN_6>;
 			linux,input-type = <EV_SW>;
 			gpios = <&gpio 6 GPIO_ACTIVE_LOW>;
 			debounce-interval = <60>;
 		};
 
 		router_off {
+			label = "router_off";
 			linux,code = <BTN_5>;
 			linux,input-type = <EV_SW>;
 			gpios = <&gpio 7 GPIO_ACTIVE_LOW>;
 			debounce-interval = <60>;
 		};
 
 		movie_engine {
+			label = "movie_engine";
 			linux,code = <BTN_7>;
 			linux,input-type = <EV_SW>;
 			gpios = <&gpio 8 GPIO_ACTIVE_LOW>;