tools: iio: iio_utils: Make calc_digits static

Signed-off-by: Joo Aun Saw <jasaw@dius.com.au>
Acked-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/tools/iio/iio_utils.c b/tools/iio/iio_utils.c
index 31aca9a..4bbd6e7 100644
--- a/tools/iio/iio_utils.c
+++ b/tools/iio/iio_utils.c
@@ -537,7 +537,7 @@
 	return ret;
 }
 
-int calc_digits(int num)
+static int calc_digits(int num)
 {
 	int count = 0;