audit: remove unnecessary #if CONFIG_AUDIT

The files which include kernel/audit.h are complied only when
CONFIG_AUDIT is set.

Just like audit_pid, there is no need to surround audit_ever_enabled
with CONFIG_AUDIT.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>