block: partition: introduce hd_free_part()

So the helper can be used in both generic partition
case and part0 case.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index ec274e0..a221220 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -663,6 +663,12 @@
 		__delete_partition(part);
 }
 
+static inline void hd_free_part(struct hd_struct *part)
+{
+	free_part_stats(part);
+	free_part_info(part);
+}
+
 /*
  * Any access of part->nr_sects which is not protected by partition
  * bd_mutex or gendisk bdev bd_mutex, should be done using this