LU-7845 lnet: check if address is visible

LU-7845 lnet: check if address is visible

In LNetDist(), check if ni's address is currently visible.
If not visible, assign order above 0xffff0000, to make this
ni not a priority.

Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I56735aa25ba632020858507939e12c4565c33d49
Reviewed-on: http://review.whamcloud.com/18782
Tested-by: Jenkins
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Li Xi <lixi@ddn.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>