arm64: dts: imx8mn: Move usdhc clocks assignment to board DT

usdhc's clock rate is different according to different devices
connected, so clock rate assignment should be placed in board
DT according to different devices connected on each usdhc port.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Abel Vesa <abel.vesa@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dts

@@ -186,6 +186,8 @@ &uart2 { /* console */
 };
 
 &usdhc2 {
+	assigned-clocks = <&clk IMX8MN_CLK_USDHC2>;
+	assigned-clock-rates = <200000000>;
 	pinctrl-names = "default", "state_100mhz", "state_200mhz";
 	pinctrl-0 = <&pinctrl_usdhc2>, <&pinctrl_usdhc2_gpio>;
 	pinctrl-1 = <&pinctrl_usdhc2_100mhz>, <&pinctrl_usdhc2_gpio>;
@@ -197,6 +199,8 @@ &usdhc2 {
 };
 
 &usdhc3 {
+	assigned-clocks = <&clk IMX8MN_CLK_USDHC3_ROOT>;
+	assigned-clock-rates = <400000000>;
 	pinctrl-names = "default", "state_100mhz", "state_200mhz";
 	pinctrl-0 = <&pinctrl_usdhc3>;
 	pinctrl-1 = <&pinctrl_usdhc3_100mhz>;

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

@@ -598,8 +598,6 @@ usdhc1: mmc@30b40000 {
 					 <&clk IMX8MN_CLK_NAND_USDHC_BUS>,
 					 <&clk IMX8MN_CLK_USDHC1_ROOT>;
 				clock-names = "ipg", "ahb", "per";
-				assigned-clocks = <&clk IMX8MN_CLK_USDHC1>;
-				assigned-clock-rates = <400000000>;
 				fsl,tuning-start-tap = <20>;
 				fsl,tuning-step= <2>;
 				bus-width = <4>;
@@ -628,8 +626,6 @@ usdhc3: mmc@30b60000 {
 					 <&clk IMX8MN_CLK_NAND_USDHC_BUS>,
 					 <&clk IMX8MN_CLK_USDHC3_ROOT>;
 				clock-names = "ipg", "ahb", "per";
-				assigned-clocks = <&clk IMX8MN_CLK_USDHC3_ROOT>;
-				assigned-clock-rates = <400000000>;
 				fsl,tuning-start-tap = <20>;
 				fsl,tuning-step= <2>;
 				bus-width = <4>;