ARM: dts: imx53-ppd: use PMIC's TSI pins in adc mode

PPD uses the PMIC's TSI pins in general purpose ADC mode.
Signed-off-by: NSebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx53-ppd.dts

@@ -132,6 +132,14 @@
 		enable-active-high;
 	};
 
+	reg_tsiref: regulator-tsiref {
+		compatible = "regulator-fixed";
+		regulator-name = "tsiref";
+		regulator-min-microvolt = <2500000>;
+		regulator-max-microvolt = <2500000>;
+		regulator-always-on;
+	};
+
 	pwm_bl: backlight {
 		compatible = "pwm-backlight";
 		pwms = <&pwm2 0 50000>;
@@ -294,6 +302,8 @@
 		interrupt-parent = <&gpio3>;
 		interrupts = <12 0x8>;
 		spi-max-frequency = <1000000>;
+		dlg,tsi-as-adc;
+		tsiref-supply = <&reg_tsiref>;
 
 		regulators {
 			buck1_reg: buck1 {