LU-6802 ptlrpc: reset imp_replay_cursor

LU-6802 ptlrpc: reset imp_replay_cursor

At client side, the replay cursor using to speed up the lookup
of committed open requests in its obd_import should be resetted
for normal connection (not reconnection) during recovery.

Change-Id: I68816780a5d79053d9109cb68ae1c3b8ea13ede8
Signed-off-by: Hongchao Zhang <hongchao.zhang@intel.com>
Reviewed-on: http://review.whamcloud.com/17351
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>