selinux: adjust rules for ATTR_FORCE

selinux: adjust rules for ATTR_FORCE

As suggested by OGAWA Hirofumi in thread:
http://lkml.org/lkml/2009/8/7/132, we should let selinux_inode_setattr()
to match our ATTR_* rules.  ATTR_FORCE should not force things like
ATTR_SIZE.

[[email protected]: tweaks]
Signed-off-by: WANG Cong <[email protected]>
Signed-off-by: OGAWA Hirofumi <[email protected]>
Acked-by: Stephen Smalley <[email protected]>
Acked-by: Eric Paris <[email protected]>
Cc: Eugene Teo <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Acked-by: James Morris <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: James Morris <[email protected]>