iio: dpot-dac: fix code comment in dpot_dac_read_raw()

After the replacement of the /* fall through */ comment with the
fallthrough pseudo-keyword macro, the natural reading of a code
comment was broken.

Fix the natural reading of such a comment and make it intelligible.
Reported-by: NPeter Rosin <peda@axentia.se>
Acked-by: NPeter Rosin <peda@axentia.se>
Signed-off-by: NGustavo A. R. Silva <gustavoars@kernel.org>

drivers/iio/dac/dpot-dac.c

@@ -74,10 +74,11 @@ static int dpot_dac_read_raw(struct iio_dev *indio_dev,
 		case IIO_VAL_INT:
 			/*
 			 * Convert integer scale to fractional scale by
-			 * setting the denominator (val2) to one, and...
+			 * setting the denominator (val2) to one...
 			 */
 			*val2 = 1;
 			ret = IIO_VAL_FRACTIONAL;
+			/* ...and fall through. Say it again for GCC. */
 			fallthrough;
 		case IIO_VAL_FRACTIONAL:
 			*val *= regulator_get_voltage(dac->vref) / 1000;