LU-5485 lnet: peer aliveness status and NI status

LU-5485 lnet: peer aliveness status and NI status

A couple of changes to improve aliveness detection:
- When LNet received a message, it can determine peer of this message
  is alive

- When LNet recieved a message from remote network, it can determine
  router is alive and NI status on router is UP.

Signed-off-by: Liang Zhen <liang.zhen@intel.com>
Change-Id: I7133987c5c8728248cce7bc0a95048b26bc6611a
Reviewed-on: http://review.whamcloud.com/12453
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Isaac Huang <he.huang@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>