apm821xx: dts: Unify naming of gpio-keys nodes

In DTS Checklist[1] we're now demanding proper generic node names, as
the name of a node should reflect the function of the device and use
generic name for that[2]. Everybody seems to be copy&pasting from DTS
files available in the repository today, so let's unify that naming
there as well and provide proper examples.

1. https://openwrt.org/submitting-patches#dts_checklist
2. https://github.com/devicetree-org/devicetree-specification/blob/master/source/devicetree-basics.rst#generic-names-recommendation

Signed-off-by: Petr Štetiar <ynezz@true.cz>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com> [split up]

target/linux/apm821xx/dts/meraki-mr24.dts

@@ -168,7 +168,7 @@
 		};
 	};
 
-	gpio_keys_polled {
+	keys {
 		compatible = "gpio-keys-polled";
 		#address-cells = <1>;
 		#size-cells = <0>;

target/linux/apm821xx/dts/meraki-mx60.dts

@@ -159,7 +159,7 @@
 		};
 	};
 
-	gpio_keys_polled {
+	keys {
 		compatible = "gpio-keys-polled";
 		#address-cells = <1>;
 		#size-cells = <0>;

target/linux/apm821xx/dts/netgear-wndap6x0.dtsi

@@ -125,7 +125,7 @@
 };
 
 &POB0 {
-	gpio_keys_polled {
+	keys {
 		compatible = "gpio-keys-polled";
 		#address-cells = <1>;
 		#size-cells = <0>;

target/linux/apm821xx/dts/netgear-wndr4700.dts

@@ -308,7 +308,7 @@
 };
 
 &POB0 {
-	gpio_keys_polled {
+	keys {
 		compatible = "gpio-keys-polled";
 		#address-cells = <1>;
 		#size-cells = <0>;

target/linux/apm821xx/dts/wd-mybooklive.dts

@@ -107,7 +107,7 @@
 		};
 	};
 
-	gpio-keys-polled {
+	keys {
 		compatible = "gpio-keys-polled";
 		#address-cells = <1>;
 		#size-cells = <0>;