[XFS] fix filestreams on 32-bit boxes

xfs_filestream_mount() sets up an mru cache with:
  err = xfs_mru_cache_create(&mp->m_filestream, lifetime, grp_count,
  (xfs_mru_cache_free_func_t)xfs_fstrm_free_func);
but that cast is causing problems...
  typedef void (*xfs_mru_cache_free_func_t)(unsigned long, void*);
but:
  void xfs_fstrm_free_func( xfs_ino_t ino, fstrm_item_t *item)
so on a 32-bit box, it's casting (32, 32) args into (64, 32) and I assume
it's getting garbage for *item, which subsequently causes an explosion.
With this change the filestreams xfsqa tests don't oops on my 32-bit box.

SGI-PV: 967795
SGI-Modid: xfs-linux-melb:xfs-kern:29510a

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>