iio: humidity: si7020: replaced bitmask on humidity values with range check

The maximum possible value for the relative humidity is 55575 (100%RH).
This value, if shifted right by 2 bits, uses 14 bits and masking it with
a 12 bit mask removes 2 meaningful bits.
The masking has been replaced with a range check that sets the minimum
value at 786 (0%RH) and the maximum at 13893 (99.998%RH).

Signed-off-by: Nicola Corna <nicola@corna.info>
Reviewed-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/humidity/si7020.c

@@ -57,8 +57,12 @@ static int si7020_read_raw(struct iio_dev *indio_dev,
 		if (ret < 0)
 			return ret;
 		*val = ret >> 2;
+		/*
+		 * Humidity values can slightly exceed the 0-100%RH
+		 * range and should be corrected by software
+		 */
 		if (chan->type == IIO_HUMIDITYRELATIVE)
-			*val &= GENMASK(11, 0);
+			*val = clamp_val(*val, 786, 13893);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		if (chan->type == IIO_TEMP)