LU-5733 lnet: Use lnet_is_route_alive for router aliveness

LU-5733 lnet: Use lnet_is_route_alive for router aliveness

lctl show_route and lctl route_list will output router aliveness
information via lnet_get_route(). lnet_get_route() should use the
lnet_is_route_alive() function, introduced in e8a1124
http://review.whamcloud.com/7857, to determine route aliveness.

Signed-off-by: Chris Horn <hornc@cray.com>
Change-Id: Ie57aebeb6b4c80a3b89ed72fc6acbccbbd321be1
Reviewed-on: http://review.whamcloud.com/14055
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Amir Shehata <amir.shehata@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>