platform-x86: intel_mid_thermal: turn off thermistor voltage by default

Instead of complaining that the voltage is on, we can just ask the MSIC to
turn the voltage off. This should save some power.

Voltage for thermistors is turned on when ADC conversion is initiated.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

drivers/platform/x86/intel_mid_thermal.c

@@ -360,8 +360,10 @@ static int mid_initialize_adc(struct device *dev)
 	if (ret)
 		return ret;
 
-	if (data & MSIC_ADCTHERM_MASK)
-		dev_warn(dev, "ADCTHERM already set");
+	data &= ~MSIC_ADCTHERM_MASK;
+	ret = intel_msic_reg_write(INTEL_MSIC_ADC1CNTL3, data);
+	if (ret)
+		return ret;
 
 	/* Index of the first channel in which the stop bit is set */
 	channel_index = find_free_channel();