LU-6802 ptlrpc: reset replay cursor on reconnection

LU-6802 ptlrpc: reset replay cursor on reconnection

In this way, clients can make sure every single replayable ptlrpc
requests will be replayed and replies will be received.

Test-Parameters: envdefinitions=PTLDEBUG=+inode mdtfilesystemtype=ldiskfs mdsfilesystemtype=ldiskfs ostfilesystemtype=ldiskfs clientdistro=el6.6 ossdistro=el6.6 mdsdistro=el6.6 mdscount=2 mdtcount=4 testlist=sanity,sanity,sanity,sanity,sanity,sanity
Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Change-Id: I32daf787d141c84376879fb0fb3b3eb8424f91ad
Reviewed-on: http://review.whamcloud.com/15669
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Hongchao Zhang <hongchao.zhang@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>