arm64: dts: rockchip: Add user button to Radxa E20C

Radxa E20C has two buttons, one SARADC maskrom button and one GPIO user
button.

Add support for the user button using a gpio-keys node.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Link: https://lore.kernel.org/r/20250304201642.831218-3-jonas@kwiboo.se
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

[ upstream commit: ad8afc8813567994164f2720189c819da8c22b99 ]

(cherry picked from commit 6793b56b79df26ab3323e5293b97577d0786ddb3)
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>

dts/upstream/src/arm64/rockchip/rk3528-radxa-e20c.dts

@@ -7,6 +7,7 @@
 
 /dts-v1/;
 
+#include <dt-bindings/input/input.h>
 #include <dt-bindings/leds/common.h>
 #include "rk3528.dtsi"
 
@@ -18,6 +19,19 @@
 		stdout-path = "serial0:1500000n8";
 	};
 
+	gpio-keys {
+		compatible = "gpio-keys";
+		pinctrl-names = "default";
+		pinctrl-0 = <&user_key>;
+
+		button-user {
+			gpios = <&gpio0 RK_PA0 GPIO_ACTIVE_LOW>;
+			label = "USER";
+			linux,code = <BTN_1>;
+			wakeup-source;
+		};
+	};
+
 	leds {
 		compatible = "gpio-leds";
 		pinctrl-names = "default";
@@ -50,6 +64,12 @@
 };
 
 &pinctrl {
+	gpio-keys {
+		user_key: user-key {
+			rockchip,pins = <0 RK_PA0 RK_FUNC_GPIO &pcfg_pull_up>;
+		};
+	};
+
 	leds {
 		lan_led_g: lan-led-g {
 			rockchip,pins = <4 RK_PB5 RK_FUNC_GPIO &pcfg_pull_none>;