opos6uldev: Convert to watchdog driver model

Commit 68dcbdd5 ("ARM: imx: Add weak default reset_cpu()") caused
the 'reset' command in U-Boot to not cause a board reset.

Fix it by switching to the watchdog driver model via sysreset, which
is the preferred method for implementing the watchdog reset.

Signed-off-by: Sébastien Szymanski <sebastien.szymanski@armadeus.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>

arch/arm/dts/imx6ul-opos6ul-u-boot.dtsi

@@ -9,6 +9,12 @@
 	soc {
 		bootph-pre-ram;
 	};
+
+	wdt-reboot {
+		compatible = "wdt-reboot";
+		wdt = <&wdog1>;
+		bootph-pre-ram;
+	};
 };
 
 &aips2 {
@@ -26,3 +32,7 @@
 &usdhc1 {
 	bootph-pre-ram;
 };
+
+&wdog1 {
+	bootph-pre-ram;
+};

configs/opos6uldev_defconfig

@@ -102,6 +102,8 @@ CONFIG_DM_REGULATOR_FIXED=y
 CONFIG_DM_REGULATOR_GPIO=y
 CONFIG_DM_SERIAL=y
 CONFIG_MXC_UART=y
+CONFIG_SYSRESET=y
+CONFIG_SYSRESET_WATCHDOG=y
 CONFIG_IMX_THERMAL=y
 CONFIG_USB=y
 CONFIG_USB_STORAGE=y
@@ -123,4 +125,5 @@ CONFIG_SPLASH_SOURCE=y
 CONFIG_BMP_16BPP=y
 CONFIG_BMP_24BPP=y
 CONFIG_BMP_32BPP=y
+CONFIG_IMX_WATCHDOG=y
 # CONFIG_EFI_LOADER is not set