arm64: dts: armada-3720: align GPIO keys node name with bindings

Bindings expect the GPIO key node names to follow certain pattern, see
dtbs_check warnings:

  armada-3720-gl-mv1000.dtb: keys: 'reset' does not match any of the regexes: '^(button|event|key|switch|(button|event|key|switch)...
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>

arch/arm64/boot/dts/marvell/armada-3720-gl-mv1000.dts

@@ -41,7 +41,7 @@ vcc_sd_reg1: regulator {
 	keys {
 		compatible = "gpio-keys";
 
-		reset {
+		button-reset {
 			label = "reset";
 			linux,code = <KEY_RESTART>;
 			gpios = <&gpionb 14 GPIO_ACTIVE_LOW>;