iio: gts: Fix uninitialized symbol 'ret'

Initialize the variable ret at the time of declaration to prevent it from
being returned without a defined value. Fixes smatch warning:
drivers/iio/industrialio-gts-helper.c:256 gain_to_scaletables() error:
uninitialized symbol 'ret'.

Cc: stable@vger.kernel.org # v6.6+
Fixes: 38416c2 ("iio: light: Add gain-time-scale helpers")
Signed-off-by: Zicheng Qu <quzicheng@huawei.com>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://patch.msgid.link/20241031014505.2313035-1-quzicheng@huawei.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: Zicheng Qu

drivers/iio/industrialio-gts-helper.c

@@ -167,7 +167,7 @@ static int iio_gts_gain_cmp(const void *a, const void *b)
 
 static int gain_to_scaletables(struct iio_gts *gts, int **gains, int **scales)
 {
-	int ret, i, j, new_idx, time_idx;
+	int i, j, new_idx, time_idx, ret = 0;
 	int *all_gains;
 	size_t gain_bytes;