iio: adc: qcom-vadc-common: use <linux/units.h> helpers

This switches the qcom-vadc-common to use milli_kelvin_to_millicelsius()
in <linux/units.h>.

Link: http://lkml.kernel.org/r/1576386975-7941-13-git-send-email-akinobu.mita@gmail.com
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Cc: Amit Kucheria <amit.kucheria@verdurent.com>
Cc: Andy Shevchenko <andy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jean Delvare <jdelvare@suse.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: Keith Busch <kbusch@kernel.org>
Cc: Luca Coelho <luciano.coelho@intel.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Sujith Thomas <sujith.thomas@intel.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

drivers/iio/adc/qcom-vadc-common.c

@@ -6,6 +6,7 @@
 #include <linux/log2.h>
 #include <linux/err.h>
 #include <linux/module.h>
+#include <linux/units.h>
 
 #include "qcom-vadc-common.h"
 
@@ -236,8 +237,7 @@ static int qcom_vadc_scale_die_temp(const struct vadc_linear_graph *calib_graph,
 		voltage = 0;
 	}
 
-	voltage -= KELVINMIL_CELSIUSMIL;
-	*result_mdec = voltage;
+	*result_mdec = milli_kelvin_to_millicelsius(voltage);
 
 	return 0;
 }
@@ -325,7 +325,7 @@ static int qcom_vadc_scale_hw_calib_die_temp(
 {
 	*result_mdec = qcom_vadc_scale_code_voltage_factor(adc_code,
 				prescale, data, 2);
-	*result_mdec -= KELVINMIL_CELSIUSMIL;
+	*result_mdec = milli_kelvin_to_millicelsius(*result_mdec);
 
 	return 0;
 }

drivers/iio/adc/qcom-vadc-common.h

@@ -38,7 +38,6 @@
 #define VADC_AVG_SAMPLES_MAX			512
 #define ADC5_AVG_SAMPLES_MAX			16
 
-#define KELVINMIL_CELSIUSMIL			273150
 #define PMIC5_CHG_TEMP_SCALE_FACTOR		377500
 #define PMIC5_SMB_TEMP_CONSTANT			419400
 #define PMIC5_SMB_TEMP_SCALE_FACTOR		356