iio: dac: ltc2632 remove redundant pointer chip_info and spi_dev_id

Pointers chip_info and spi_dev_id are being assigned but are never used
hence they are redundant and can be removed.

Cleans up clang warning:
warning: variable 'chip_info' set but not used [-Wunused-but-set-variable]
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/dac/ltc2632.c

@@ -87,12 +87,7 @@ static int ltc2632_read_raw(struct iio_dev *indio_dev,
 			    int *val2,
 			    long m)
 {
-	struct ltc2632_chip_info *chip_info;
-
 	const struct ltc2632_state *st = iio_priv(indio_dev);
-	const struct spi_device_id *spi_dev_id = spi_get_device_id(st->spi_dev);
-
-	chip_info = (struct ltc2632_chip_info *)spi_dev_id->driver_data;
 
 	switch (m) {
 	case IIO_CHAN_INFO_SCALE: