cpufreq: imx-cpufreq-dt: Correct i.MX8MN's default speed grade value

i.MX8MN has different speed grade definition compared to
i.MX8MQ/i.MX8MM, when fuses are NOT written, the default
speed_grade should be set to minimum available OPP defined
in DT which is 1.2GHz, the corresponding speed_grade value
should be 0xb.

Fixes: 5b8010ba70d5 ("cpufreq: imx-cpufreq-dt: Add i.MX8MN support")
Signed-off-by: Anson Huang <[e-mail]>
Signed-off-by: Viresh Kumar <[e-mail]>

drivers/cpufreq/imx-cpufreq-dt.c

···
 	mkt_segment = (cell_value & OCOTP_CFG3_MKT_SEGMENT_MASK) >> OCOTP_CFG3_MKT_SEGMENT_SHIFT;
 
 	/*
-	 * Early samples without fuses written report "0 0" which means
-	 * consumer segment and minimum speed grading.
-	 *
-	 * According to datasheet minimum speed grading is not supported for
-	 * consumer parts so clamp to 1 to avoid warning for "no OPPs"
+	 * Early samples without fuses written report "0 0" which may NOT
+	 * match any OPP defined in DT. So clamp to minimum OPP defined in
+	 * DT to avoid warning for "no OPPs".
 	 *
 	 * 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;
+	if (mkt_segment == 0 && speed_grade == 0) {
+		if (of_machine_is_compatible("fsl,imx8mm") ||
+		    of_machine_is_compatible("fsl,imx8mq"))
+			speed_grade = 1;
+		if (of_machine_is_compatible("fsl,imx8mn"))
+			speed_grade = 0xb;
+	}
 
 	supported_hw[0] = BIT(speed_grade);
 	supported_hw[1] = BIT(mkt_segment);