ARM: dts: imx50-kobo-aura: Add Netronix embedded controller

Enable the Netronix EC on the Kobo Aura ebook reader.

Several features are still missing:
 - Frontlight/backlight. The vendor kernel drives the frontlight LED
   using the PWM output of the EC and an additional boost pin that
   increases the brightness.
 - Battery monitoring
 - Interrupts for RTC alarm and low-battery events
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx50-kobo-aura.dts

@@ -143,10 +143,24 @@ &i2c3 {
 	pinctrl-0 = <&pinctrl_i2c3>;
 	status = "okay";
 
-	/* TODO: embedded controller at 0x43 */
+	embedded-controller@43 {
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_ec>;
+		compatible = "netronix,ntxec";
+		reg = <0x43>;
+		system-power-controller;
+		interrupts-extended = <&gpio4 11 IRQ_TYPE_EDGE_FALLING>;
+		#pwm-cells = <2>;
+	};
 };
 
 &iomuxc {
+	pinctrl_ec: ecgrp {
+		fsl,pins = <
+			MX50_PAD_CSPI_SS0__GPIO4_11		0x0	/* INT */
+		>;
+	};
+
 	pinctrl_gpiokeys: gpiokeysgrp {
 		fsl,pins = <
 			MX50_PAD_CSPI_MISO__GPIO4_10		0x0