dlm: revert atomic_t lkb_wait_count

Revert "fs: dlm: handle lkb wait count as atomic_t"
This reverts commit 75a7d601.

This counter does not need to be atomic.  As the comment in
the reverted commit mentions, the counter is protected by
the rsb lock.

Signed-off-by: David Teigland <teigland@redhat.com>