iio:light:cm3323: pass up error value

cm3323_get_it_bits() returns a valid error code, so pass it up in
cm3323_read_raw().
Signed-off-by: Hartmut Knaack <knaack.h@gmx.de>
Reviewed-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/light/cm3323.c

@@ -175,7 +175,7 @@ static int cm3323_read_raw(struct iio_dev *indio_dev,
 		i = cm3323_get_it_bits(data);
 		if (i < 0) {
 			mutex_unlock(&data->mutex);
-			return -EINVAL;
+			return i;
 		}
 
 		*val = cm3323_int_time[i].val;