IIO: Documentation: iio_utils: Avoid double free()

filename is used and freed later
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/Documentation/iio_utils.h

@@ -319,7 +319,6 @@ inline int build_channel_array(const char *device_dir,
 			}
 			fscanf(sysfsfp, "%u", &current->enabled);
 			fclose(sysfsfp);
-			free(filename);
 			current->scale = 1.0;
 			current->offset = 0;
 			current->name = strndup(ent->d_name,