cpufreq: imx-cpufreq-dt: Add i.MX8MN support

i.MX8MN is a new SoC of i.MX8M series, it also uses speed
grading and market segment fuses for OPP definitions, add
support for this SoC.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/imx-cpufreq-dt.c

@@ -44,10 +44,11 @@ static int imx_cpufreq_dt_probe(struct platform_device *pdev)
 	 * According to datasheet minimum speed grading is not supported for
 	 * consumer parts so clamp to 1 to avoid warning for "no OPPs"
 	 *
-	 * Applies to 8mq and 8mm.
+	 * Applies to i.MX8M series SoCs.
 	 */
 	if (mkt_segment == 0 && speed_grade == 0 && (
 			of_machine_is_compatible("fsl,imx8mm") ||
+			of_machine_is_compatible("fsl,imx8mn") ||
 			of_machine_is_compatible("fsl,imx8mq")))
 		speed_grade = 1;