ARM: dts: at91: sama5d2_xplained: set PB_USER as wakeup source

Set the PB_USER button as a wakeup source to resume from ulp0 mode.
Signed-off-by: NLudovic Desroches <ludovic.desroches@microchip.com>
[claudiu.beznea@microchip.com: change subject to match the desired prefix]
Signed-off-by: NClaudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>

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

@@ -531,6 +531,7 @@
 			label = "PB_USER";
 			gpios = <&pioA PIN_PB9 GPIO_ACTIVE_LOW>;
 			linux,code = <0x104>;
+			wakeup-source;
 		};
 	};