ARM: at91/dt: at91sam9x5dm: add support for the touschscreen

The display module on the at91sam9x5-ek has a resistive touchscreen, add
it.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

arch/arm/boot/dts/at91sam9x5dm.dtsi

@@ -25,6 +25,12 @@ hlcdc_panel_output: endpoint@0 {
 					};
 				};
 			};
+
+			adc0: adc@f804c000 {
+				atmel,adc-ts-wires = <4>;
+				atmel,adc-ts-pressure-threshold = <10000>;
+				status = "okay";
+			};
 		};
 	};