ARM: dts: imx6sx-sabreauto: add wdog external reset

i.MX6SX Sabre Auto board has GPIO1_IO13 pin can be
MUXed as WDOG output to reset PMIC, add this function
support.
Signed-off-by: NAnson Huang <Anson.Huang@nxp.com>
Reviewed-by: NFabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6sx-sabreauto.dts

@@ -221,6 +221,12 @@
 			MX6SX_PAD_KEY_COL1__GPIO2_IO_11		0x17059
 		>;
 	};
+
+	pinctrl_wdog: wdoggrp {
+		fsl,pins = <
+			MX6SX_PAD_GPIO1_IO13__WDOG1_WDOG_ANY	0x30b0
+		>;
+	};
 };
 
 &i2c2 {
@@ -359,3 +365,9 @@
 		#gpio-cells = <2>;
 	};
 };
+
+&wdog1 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_wdog>;
+	fsl,ext-reset-output;
+};