smack: remove /smack/logging if audit is not configured

If CONFIG_AUDIT is not set then
SMACK does not generate audit messages,
however, keeps audit control file, /smack/logging,
while there is no entity to control.
This change removes audit control file /smack/logging
when audit is not configured in the kernel

Signed-off-by: Konstantin Andreev <andreev@swemel.ru>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>