arm64: dts: imx8mp: Add fallback compatible to ocotp node

Add "fsl,imx8mm-ocotp" as fallback compatible of i.MX8MP ocotp
to support SoC serial_number read.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mp.dtsi

@@ -314,7 +314,7 @@ gpr: iomuxc-gpr@30340000 {
 			};
 
 			ocotp: efuse@30350000 {
-				compatible = "fsl,imx8mp-ocotp", "syscon";
+				compatible = "fsl,imx8mp-ocotp", "fsl,imx8mm-ocotp", "syscon";
 				reg = <0x30350000 0x10000>;
 				clocks = <&clk IMX8MP_CLK_OCOTP_ROOT>;
 				/* For nvmem subnodes */