iio: magnetometer: mmc35240: Fix function header formatting

All lines in the header must start with " *".

Fixes the following W=1 kernel build warning(s):

 drivers/iio/magnetometer/mmc35240.c:304: warning: bad line:                             compensation for output value.

Cc: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/magnetometer/mmc35240.c

@@ -301,7 +301,7 @@ static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
 
 /**
  * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply
-			    compensation for output value.
+ *			    compensation for output value.
  *
  * @data: device private data
  * @index: axis index for which we want the conversion