xfs: fix the comment of xfs_bmap_count_tree()

Signed-off-by: NZhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Reviewed-by: NMark Tinguely <tinguely@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>

fs/xfs/xfs_bmap_util.c

@@ -357,7 +357,7 @@ xfs_bmap_disk_count_leaves(
 
 /*
  * 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(