NFS: Don't let nfs_end_data_update() clobber attribute update information

 Since we almost always call nfs_end_data_update() after we called
 nfs_refresh_inode(), we now end up marking the inode metadata
 as needing revalidation immediately after having updated it.

 This patch rearranges things so that we mark the inode as needing
 revalidation _before_ we call nfs_refresh_inode() on those operations
 that need it.

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