xfs: fix the comment of xfs_bmap_count_tree()

Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index cc2ab9b..b681591 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -357,7 +357,7 @@
 
 /*
  * Recursively walks each level of a btree
- * to count total fsblocks is use.
+ * to count total fsblocks in use.
  */
 STATIC int                                     /* error */
 xfs_bmap_count_tree(