[PATCH] simplify audit_free() locking

Simplify audit_free()'s locking: no need to lock a task that we are tearing
down.  [the extra locking also caused false positives in the lock
validator]

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>