ARM: dts: imx: Add WDT reboot bindings on DH i.MX6 DHSOM

Add WDT reboot bindings on DH i.MX6 DHSOM to permit the platform
to reboot via WDT in U-Boot. These are custom U-Boot bindings,
hence they are placed in -u-boot.dtsi .

Reviewed-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Marek Vasut <marex@denx.de>
diff --git a/arch/arm/dts/imx6qdl-dhcom-u-boot.dtsi b/arch/arm/dts/imx6qdl-dhcom-u-boot.dtsi
index 190567a..740a24d 100644
--- a/arch/arm/dts/imx6qdl-dhcom-u-boot.dtsi
+++ b/arch/arm/dts/imx6qdl-dhcom-u-boot.dtsi
@@ -8,6 +8,12 @@
 	aliases {
 		eeprom0 = &eeprom0;
 	};
+
+	wdt-reboot {
+		compatible = "wdt-reboot";
+		wdt = <&wdog1>;
+		bootph-pre-ram;
+	};
 };
 
 &fec {
@@ -25,3 +31,7 @@
 	gpio = <&gpio3 31 GPIO_ACTIVE_HIGH>;
 	enable-active-high;
 };
+
+&wdog1 {
+	bootph-pre-ram;
+};