audit: wake up kauditd_thread after auditd registers

This patch was suggested by Richard Briggs back in 2015, see the link
to the mail archive below.  Unfortunately, that patch is no longer
even remotely valid due to other changes to the code.

* https://www.redhat.com/archives/linux-audit/2015-October/msg00075.html



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