staging/lustre/lnet: Add LNet Router Priority parameter

This change adds a priority parameter to the route module settings.
This paramter can be >= 0. Like hops, the lower the prioirty number
the higher the priority.  So lower numbered priorities will be
selected over higher numbers.

Lustre-change: http://review.whamcloud.com/5663
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-2934


Signed-off-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Amir Shehata <amir.shehata@intel.com>
Reviewed-by: Isaac Huang <he.huang@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Peng Tao <bergwolf@gmail.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>