ARM: dts: am437x: make edt-ft5x06 a wakeup source

The touchscreen driver no longer configures the device as wakeup source by
default. A "wakeup-source" property is needed.
Signed-off-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/am437x-sk-evm.dts

@@ -610,6 +610,8 @@ edt-ft5306@38 {
 
 		touchscreen-size-x = <480>;
 		touchscreen-size-y = <272>;
+
+		wakeup-source;
 	};
 
 	tlv320aic3106: tlv320aic3106@1b {