ARM: dts: imx6sx-sdb: Use WDOG_B pin reset

imx6sx-sdb has WDOG1_B pin connected to the PMIC.

Pass the 'fsl,ext-reset-output' property so that the watchdog
can trigger a system POR reset via the PMIC.
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6sx-sdb.dtsi

@@ -322,6 +322,12 @@ &usdhc4 {
 	status = "okay";
 };
 
+&wdog1 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_wdog>;
+	fsl,ext-reset-output;
+};
+
 &iomuxc {
 	imx6x-sdb {
 		pinctrl_audmux: audmuxgrp {
@@ -588,5 +594,11 @@ MX6SX_PAD_SD4_DATA7__GPIO6_IO_21	0x17059 /* CD */
 				MX6SX_PAD_SD4_DATA6__GPIO6_IO_20	0x17059 /* WP */
 			>;
 		};
+
+		pinctrl_wdog: wdoggrp {
+			fsl,pins = <
+				MX6SX_PAD_GPIO1_IO13__WDOG1_WDOG_ANY 0x30b0
+			>;
+		};
 	};
 };