staging: lustre: set downis to 1 if there's no NI for remote net

staging: lustre: set downis to 1 if there's no NI for remote net

lnet_route_t::lr_downis is marked as zero even if there is no NI to
target network, this is wrong and breaks logic of ARF. This patch
fixes this problem.

Signed-off-by: Liang Zhen <liang.zhen@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6060
Reviewed-on: http://review.whamcloud.com/13417
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>