lockdep: fix internal double unlock during self-test

Lockdep, during self-test (when it was simulating double unlocks) was
sometimes unconditionally unlocking a spinlock when it had not been
locked. This won't work for ticket locks.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>