LU-7836 ptlrpc: remove duplicate final ping req

LU-7836 ptlrpc: remove duplicate final ping req

Remove duplidate final ping req if the failover
server get new final ping from the same client,
otherwise the final ping will be piled up on
the recovery server, especially if recovery is
stuck during DNE failover.

Signed-off-by: Di Wang <di.wang@intel.com>
Change-Id: I41ecc88cede1024d386283e693698789ac0b7aa4
Reviewed-on: http://review.whamcloud.com/19693
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>