arm64: dts: imx8mm: Add cpufreq properties

This is very similar to imx8mq cpufreq-dt support.

Operating points are from datasheet:
https://www.nxp.com/docs/en/data-sheet/IMX8MMCEC.pdf

Higher opps were omitted (just like imx8mq) because it requires checking
speed grade from OCOTP fuses.
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

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

@@ -48,32 +48,44 @@ A53_0: cpu@0 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a53";
 			reg = <0x0>;
+			clock-latency = <61036>; /* two CLK32 periods */
+			clocks = <&clk IMX8MM_CLK_ARM>;
 			enable-method = "psci";
 			next-level-cache = <&A53_L2>;
+			operating-points-v2 = <&a53_opp_table>;
 		};
 
 		A53_1: cpu@1 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a53";
 			reg = <0x1>;
+			clock-latency = <61036>; /* two CLK32 periods */
+			clocks = <&clk IMX8MM_CLK_ARM>;
 			enable-method = "psci";
 			next-level-cache = <&A53_L2>;
+			operating-points-v2 = <&a53_opp_table>;
 		};
 
 		A53_2: cpu@2 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a53";
 			reg = <0x2>;
+			clock-latency = <61036>; /* two CLK32 periods */
+			clocks = <&clk IMX8MM_CLK_ARM>;
 			enable-method = "psci";
 			next-level-cache = <&A53_L2>;
+			operating-points-v2 = <&a53_opp_table>;
 		};
 
 		A53_3: cpu@3 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a53";
 			reg = <0x3>;
+			clock-latency = <61036>; /* two CLK32 periods */
+			clocks = <&clk IMX8MM_CLK_ARM>;
 			enable-method = "psci";
 			next-level-cache = <&A53_L2>;
+			operating-points-v2 = <&a53_opp_table>;
 		};
 
 		A53_L2: l2-cache0 {
@@ -81,6 +93,24 @@ A53_L2: l2-cache0 {
 		};
 	};
 
+	a53_opp_table: opp-table {
+		compatible = "operating-points-v2";
+		opp-shared;
+
+		opp-1200000000 {
+			opp-hz = /bits/ 64 <1200000000>;
+			opp-microvolt = <850000>;
+			clock-latency-ns = <150000>;
+		};
+
+		opp-1600000000 {
+			opp-hz = /bits/ 64 <1600000000>;
+			opp-microvolt = <900000>;
+			clock-latency-ns = <150000>;
+			opp-suspend;
+		};
+	};
+
 	memory@40000000 {
 		device_type = "memory";
 		reg = <0x0 0x40000000 0 0x80000000>;