arm64: dts: imx8qxp: Move watchdog node into scu node

i.MX system controller watchdog has pretimeout function which
depends on i.MX SCU driver, so it should be a subnode of SCU.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8qxp.dtsi

@@ -157,6 +157,11 @@ pd: imx8qx-pd {
 		rtc: rtc {
 			compatible = "fsl,imx8qxp-sc-rtc";
 		};
+
+		watchdog {
+			compatible = "fsl,imx8qxp-sc-wdt", "fsl,imx-sc-wdt";
+			timeout-sec = <60>;
+		};
 	};
 
 	timer {
@@ -525,9 +530,4 @@ lsio_gpio7: gpio@5d0f0000 {
 			power-domains = <&pd IMX_SC_R_GPIO_7>;
 		};
 	};
-
-	watchdog {
-		compatible = "fsl,imx8qxp-sc-wdt", "fsl,imx-sc-wdt";
-		timeout-sec = <60>;
-	};
 };