arm64: dts: imx8mm: Remove incorrect fallback compatible for ocotp

Compared to i.MX7D, i.MX8MM has different ocotp layout, so it should
NOT use "fsl,imx7d-ocotp" as ocotp's fallback compatible, remove it.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mm.dtsi

@@ -426,7 +426,7 @@ gpr: iomuxc-gpr@30340000 {
 			};
 
 			ocotp: ocotp-ctrl@30350000 {
-				compatible = "fsl,imx8mm-ocotp", "fsl,imx7d-ocotp", "syscon";
+				compatible = "fsl,imx8mm-ocotp", "syscon";
 				reg = <0x30350000 0x10000>;
 				clocks = <&clk IMX8MM_CLK_OCOTP_ROOT>;
 				/* For nvmem subnodes */