staging/lustre/ptlrpc: fix import state during replay

Client doesn't restore import state correctly
on reconnect during replay. It resends lock replay
when final ping was queued by server.
Server fails with "target_queue_recovery_request())
ASSERTION( req->rq_export->exp_lock_replay_needed ) failed"

Add imp_replay_state to store last replay state.
imp_state is restored from imp_replay_state
during reconnect.

Signed-off-by: Andriy Skulysh <Andriy_Skulysh@xyratex.com>
Signed-off-by: Bob Glossman <bob.glossman@intel.com>
Xyratex-bug-id: MRP-2022
Reviewed-on: http://review.whamcloud.com/12163
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5651


Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>