arm64: dts: meson-gxm-khadas-vim2: fix gpio-keys-polled node

Fix DTC warnings:

meson-gxm-khadas-vim2.dtb: Warning (avoid_unnecessary_addr_size):
   /gpio-keys-polled: unnecessary #address-cells/#size-cells
	without "ranges" or child "reg" property

Fixes: b8b74dda ("ARM64: dts: meson-gxm: Add support for Khadas VIM2")
Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

arch/arm64/boot/dts/amlogic/meson-gxm-khadas-vim2.dts

@@ -63,11 +63,9 @@ gpio_fan: gpio-fan {
 
 	gpio-keys-polled {
 		compatible = "gpio-keys-polled";
-		#address-cells = <1>;
-		#size-cells = <0>;
 		poll-interval = <100>;
 
-		button@0 {
+		power-button {
 			label = "power";
 			linux,code = <KEY_POWER>;
 			gpios = <&gpio_ao GPIOAO_2 GPIO_ACTIVE_LOW>;