imx8mn: Add LPDDR4 EVK board support

Add support for iMX8MN LPDDR4 EVK board which uses 2GB LPDDR4 and
PCA9450B PMIC.

Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/dts/imx8mn-ddr4-evk-u-boot.dtsi b/arch/arm/dts/imx8mn-ddr4-evk-u-boot.dtsi
index 025090f..8cd15be 100644
--- a/arch/arm/dts/imx8mn-ddr4-evk-u-boot.dtsi
+++ b/arch/arm/dts/imx8mn-ddr4-evk-u-boot.dtsi
@@ -19,6 +19,9 @@
 &clk {
 	u-boot,dm-spl;
 	u-boot,dm-pre-reloc;
+	/delete-property/ assigned-clocks;
+	/delete-property/ assigned-clock-parents;
+	/delete-property/ assigned-clock-rates;
 };
 
 &osc_24m {