ARM: dts: at91: sama5d2 Xplained: add user push button

Add the push button named "PB USER" with code 0x104. Associated pinctrl node is
also added.
Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/boot/dts/at91-sama5d2_xplained.dts

@@ -302,6 +302,11 @@ pinctrl_i2c1_default: i2c1_default {
 					bias-disable;
 				};
 
+				pinctrl_key_gpio_default: key_gpio_default {
+					pinmux = <PIN_PB9__GPIO>;
+					bias-pull-up;
+				};
+
 				pinctrl_macb0_default: macb0_default {
 					pinmux = <PIN_PB14__GTXCK>,
 						 <PIN_PB15__GTXEN>,
@@ -400,4 +405,17 @@ pinctrl_usba_vbus: usba_vbus {
 			};
 		};
 	};
+
+	gpio_keys {
+		compatible = "gpio-keys";
+
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_key_gpio_default>;
+
+		bp1 {
+			label = "PB_USER";
+			gpios = <&pioA 41 GPIO_ACTIVE_LOW>;
+			linux,code = <0x104>;
+		};
+	};
 };