hwmon: (ntc_thermistor) Drop unused headers.

The IIO usage in this driver is purely consumer so it should only
be including linux/iio/consumer.h  Whilst here drop pm_runtime.h
as there is no runtime power management in the driver.

Found using include-what-you-use and manual inspection of the
suggestions.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210611142257.103094-1-jic23@kernel.orgSigned-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/ntc_thermistor.c

@@ -8,7 +8,6 @@
 
 #include <linux/slab.h>
 #include <linux/module.h>
-#include <linux/pm_runtime.h>
 #include <linux/math64.h>
 #include <linux/platform_device.h>
 #include <linux/err.h>
@@ -17,9 +16,6 @@
 
 #include <linux/platform_data/ntc_thermistor.h>
 
-#include <linux/iio/iio.h>
-#include <linux/iio/machine.h>
-#include <linux/iio/driver.h>
 #include <linux/iio/consumer.h>
 
 #include <linux/hwmon.h>