audit: purge unnecessary list_empty calls

The original conditions that led to the use of list_empty() to optimize
list_for_each_entry_rcu() in auditfilter.c and auditsc.c code have been
removed without removing the list_empty() call, but this code example
has been copied several times.  Remove the unnecessary list_empty()
calls.

Please see upstream github issue
https://github.com/linux-audit/audit-kernel/issues/112



Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>