thermal/drivers/imx8mm: Enable ADC when enabling monitor

The i.MX 8MP has a ADC_PD bit in the TMU_TER register that controls the
operating mode of the ADC:
* 0 means normal operating mode
* 1 means power down mode

When enabling/disabling the TMU, the ADC operating mode must be set
accordingly.

i.MX 8M Mini & Nano are lacking this bit.

REFERENCE:
https://git.toradex.com/cgit/linux-toradex.git/commit/drivers/thermal/imx8mm_thermal.c?h=toradex_5.15-2.2.x-imx&id=4c12feec2dfde62dea8dabe1d2dd78ee340ba048

drivers/thermal/imx8mm_thermal.c

@@ -22,6 +22,7 @@
 #define TPS			0x4
 #define TRITSR			0x20	/* TMU immediate temp */
 
+#define TER_ADC_PD		BIT(30)
 #define TER_EN			BIT(31)
 #define TRITSR_TEMP0_VAL_MASK	0xff
 #define TRITSR_TEMP1_VAL_MASK	0xff0000
@@ -163,6 +164,8 @@ static void imx8mm_tmu_enable(struct imx8mm_tmu *tmu, bool enable)
 
 	val = readl_relaxed(tmu->base + TER);
 	val = enable ? (val | TER_EN) : (val & ~TER_EN);
+	if (tmu->socdata->version == TMU_VER2)
+		val = enable ? (val & ~TER_ADC_PD) : (val | TER_ADC_PD);
 	writel_relaxed(val, tmu->base + TER);
 }