On AArch64, audit is supported through generic lib/audit.c and
compat_audit.c, and so this patch adds arch specific definitions required.

Acked-by Will Deacon <will.deacon@arm.com>
Acked-by: NRichard Guy Briggs <rgb@redhat.com>
Signed-off-by: NAKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>