LU-11475 lnet: transfer routers

LU-11475 lnet: transfer routers

When a primary NID of a peer is about to be deleted because
it's being transfered to another peer, if that peer is a gateway
then transfer all gateway properties to the new peer.

Test-Parameters: forbuildonly
Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Change-Id: Ib475c389ca5630906416a5112b3088f6f5d03950
Reviewed-on: https://review.whamcloud.com/34539
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Olaf Weber <olaf.weber@hpe.com>
Tested-by: Jenkins