LU-3679 lnet: reflect down routes in /proc/sys/lnet/routes

LU-3679 lnet: reflect down routes in /proc/sys/lnet/routes

We consider routes "down" if the router is down or the router
NI for the target network is down. This should be reflected
in the output of /proc/sys/lnet/routes

Signed-off-by: Chris Horn <hornc@cray.com>
Change-Id: I82ee769d88aec92f1690ad9c095e32c9a9f9e282
Reviewed-on: http://review.whamcloud.com/7857
Reviewed-by: Cory Spitz <spitzcor@cray.com>
Reviewed-by: Isaac Huang <he.huang@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>