TAKE - fix assert in 2.5 pagebuf code

[Steve Lord <lord@xxxxxxx>]

fix 2.5 specific code for small block size filesystems, there was a
case where a page sized block filesystem went down to the small
blocksize code path.


Date:  Fri Oct  4 12:35:07 PDT 2002
Workarea:  jen.americas.sgi.com:/src/lord/xfs-merge.2.5

The following file(s) were checked into:
  bonnie.engr.sgi.com:/isms/slinx/2.5.x-xfs


Modid:  2.5.x-xfs:slinx:129109a
linux/fs/xfs/pagebuf/page_buf.c - 1.64
        - if the lookup_pages path, do not descend into using page->private
          for a bitmask for the page sized filesystem blocksize case.