ath79: etactica-eg200: fix restore button

The button is labelled reboot/restore in documentation, and has always
been used for that.  Naming it WPS has always been wrong.

Signed-off-by: Karl Pálsson <karlp@etactica.com>
[matched author with SoB]
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>

target/linux/ath79/dts/ar9331_etactica_eg200.dts

@@ -19,7 +19,7 @@
 		poll-interval = <50>;
 
 		restore {
-			linux,code = <KEY_WPS_BUTTON>;
+			linux,code = <KEY_RESTART>;
 			gpios = <&gpio 11 GPIO_ACTIVE_LOW>;
 		};
 	};