remove checks now in the VFS

XFS has an additional xattr interface through obscure ioctl.  it requires
raised capabilities but we need to add some read-only/immutable checks anyway

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Nathan Scott <nathans@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>