bio_put(): add bio_clone() to the list of functions in the comment

In bio_put()'s comment, add bio_clone() to the list of functions that can
give you a bio reference.

Signed-off-by: Alberto Bertogli <albertito@blitiri.com.ar>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fs/bio.c b/fs/bio.c
index 402cb84..bcab9e9 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -407,7 +407,7 @@
  *
  * Description:
  *   Put a reference to a &struct bio, either one you have gotten with
- *   bio_alloc or bio_get. The last put of a bio will free it.
+ *   bio_alloc, bio_get or bio_clone. The last put of a bio will free it.
  **/
 void bio_put(struct bio *bio)
 {