apparmor: Remove deadcode

aa_label_audit, aa_label_find, aa_label_seq_print and aa_update_label_name
were added by commit
f1bd9041 ("apparmor: add the base fns() for domain labels")
but never used.

aa_profile_label_perm was added by commit
637f688d ("apparmor: switch from profiles to using labels on contexts")
but never used.

aa_secid_update was added by commit
c0929212 ("apparmor: add support for mapping secids and using secctxes")
but never used.

aa_split_fqname has been unused since commit
3664268f ("apparmor: add namespace lookup fns()")

aa_lookup_profile has been unused since commit
93c98a48 ("apparmor: move exec domain mediation to using labels")

aa_audit_perms_cb was only used by aa_profile_label_perm (see above).

All of these commits are from around 2017.

Remove them.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: John Johansen <john.johansen@canonical.com>