LU-11299 lnet: use discovery for routing

LU-11299 lnet: use discovery for routing

Instead of re-inventing the wheel, routing now uses discovery.
Every router interval the router is discovered. This will
update the router information locally and will serve to let the
router know that the peer is alive.

Test-Parameters: forbuildonly
Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Change-Id: I211bf15af0b0a5d50f9e2a69a385419a1dd5096b
Reviewed-on: https://review.whamcloud.com/33454
Reviewed-by: Olaf Weber <olaf.weber@hpe.com>
Tested-by: Jenkins