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>

tools/iio/iio_utils.c

@@ -537,7 +537,7 @@ error_free_name:
 	return ret;
 }
 
-int calc_digits(int num)
+static int calc_digits(int num)
 {
 	int count = 0;