remove 8 bytes of padding from struct nfs_fattr on 64 bit builds

This also removes padding from several nfs structures, including
16 bytes from  nfs4_opendata, nfs4_createdata,nfs3_createdata
& 8 bytes from nfs_read_data,nfs_write_data,nfs_removeres,nfs4_closedata

This also reduces the reported stack usage of many nfs functions (30+).

Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
----

This patch is against the latest git 2.6.27-rc4.
I've built & run this on my AMD64 desktop, & successfully run _simple_
tests with a  64 bit client => 32 bit server & 32 bit client to 64 bit
server.

On fedora with gcc (GCC) 4.3.0 20080428 (Red Hat 4.3.0-8) checkpatch
reports 33 functions with reduced stack usage.
e.g.
__nfs_revalidate_inode [nfs] 216 => 200
_nfs4_proc_access [nfs] 304 => 288
_nfs4_proc_link [nfs] 536 => 504
_nfs4_proc_remove [nfs] 304 => 288
_nfs4_proc_rename [nfs] 584 => 552
nfs3_proc_access [nfs] 272 => 256
nfs3_proc_getacl [nfs] 384 => 368
nfs3_proc_link [nfs] 496 => 464
etc
I can supply the complete list if anyone is interested.

regards
Richard
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>