SELinux: remove current object class and permission validation mechanism

Removes the current SELinux object class and permission validation code,
as the current code makes it impossible to change or remove object classes
and permissions on a running system. Additionally, the current code does
not actually validate that the classes and permissions are correct, but
instead merely validates that they do not change between policy reloads.

Signed-off-by: Chad Sellers <csellers@tresys.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>