LU-11851 ldiskfs: reschedule for htree thread.

LU-11851 ldiskfs: reschedule for htree thread.

Thread may be waken inproperly in htree code. This patch
reschedule thread to keep locking correct.

Lustre-change: https://review.whamcloud.com/34160
Lustre-commit: 892f62c7a20d87954744c6c8937960379a870992

Change-Id: I6a8d1bbc0470b2577ca80faa304eb06f7913c218
Signed-off-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Wang Shilong <wshilong@ddn.com>
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/35006
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>