[PATCH] lockdep: clean up completion initializer in smpboot.c

Clean up lockdep on-stack-completion initializer.  (This also removes the
dependency on waitqueue_lock_key.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>