xfs: fix the comment of xfs_buf_free()

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_buf.c b/fs/xfs/xfs_buf.c
index c8136d0..118ce71 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -304,7 +304,7 @@
  *	Releases the specified buffer.
  *
  * 	The modification state of any associated pages is left unchanged.
- * 	The buffer most not be on any hash - use xfs_buf_rele instead for
+ * 	The buffer must not be on any hash - use xfs_buf_rele instead for
  * 	hashed and refcounted buffers
  */
 void