arm64: dts: imx8mn: add ddr pmu node

Add ddr pmu node for i.MX8MN EVK board.
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mn.dtsi

@@ -763,6 +763,12 @@ gic: interrupt-controller@38800000 {
 			interrupt-controller;
 			interrupts = <GIC_PPI 9 IRQ_TYPE_LEVEL_HIGH>;
 		};
+
+		ddr-pmu@3d800000 {
+			compatible = "fsl,imx8mn-ddr-pmu", "fsl,imx8m-ddr-pmu";
+			reg = <0x3d800000 0x400000>;
+			interrupts = <GIC_SPI 98 IRQ_TYPE_LEVEL_HIGH>;
+		};
 	};
 
 	usbphynop1: usbphynop1 {