LU-7079 ptlrpc: imp_peer_committed_transno should increase

LU-7079 ptlrpc: imp_peer_committed_transno should increase

imp_peer_committed_transno should not decrease as this can
confuse the users if imp_peer_committed_transno is used to
check commit status.

Change-Id: I8a1fdc651d837987bbe9aecc859b36849f9ee0a7
Signed-off-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-on: http://review.whamcloud.com/16161
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: wangdi <di.wang@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>