ramips: rename keys node formerly named button

For some devices, the keys node is named "button". Change name to
match the rest of the target.

Signed-off-by: Adrian Schmutzler <[email protected]>

target/linux/ramips/dts/mt7621_xiaomi_mir3g-v2.dts

@@ -35,7 +35,7 @@
 		};
 	};
 
-	button {
+	keys {
 		compatible = "gpio-keys";
 
 		reset {

target/linux/ramips/dts/mt7621_xiaomi_mir3g.dts

@@ -54,7 +54,7 @@
 		};
 	};
 
-	button {
+	keys {
 		compatible = "gpio-keys";
 
 		reset {

target/linux/ramips/dts/mt7621_xiaomi_mir3p.dts

@@ -60,7 +60,7 @@
 		};
 	};
 
-	button {
+	keys {
 		compatible = "gpio-keys";
 
 		reset {