iv_wait: iv_wait_completion() lock dropping fix.
iv_wait: iv_wait_completion() lock dropping fix.

Commit "iv_wait: iv_wait_completion() needs lock protection."
added lock protection to iv_wait_completion(), but forgot to drop
iv_wait_lock in the self-unregister case, causing that lock to be
kept held, and leading to mayhem all around.

Signed-off-by: Lennert Buytenhek <8858498612e3a522354216649776e3032dcb7e5b@wantstofly.org>

buytenh/ivykis,buytenh/ivykis