xfs: fix the comment of xfs_bmap_punch_delalloc_range()

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

@@ -764,7 +764,7 @@ xfs_getbmap(
 /*
  * dead simple method of punching delalyed allocation blocks from a range in
  * the inode. Walks a block at a time so will be slow, but is only executed in
- * rare error cases so the overhead is not critical. This will alays punch out
+ * rare error cases so the overhead is not critical. This will always punch out
  * both the start and end blocks, even if the ranges only partially overlap
  * them, so it is up to the caller to ensure that partial blocks are not
  * passed in.