ovn: specify addresses of type "router" lsps as "router"

ovn: specify addresses of type "router" lsps as "router"

Currently in OVN, when a logical switch port of type "router" is
created, the MAC and optionally IP addresses of the peer logical
router port must be specified again as the addresses of the logical
switch port.

This patch allows the logical switch port's addresses to be
specified as the string "router", rather than explicitly copying the
logical router port's MAC and optionally IP addresses.  The router
addresses are used to populate the logical switch's destination
lookup, and to populate op->lsp_addrs in ovn-northd.c, which in turn
is used to generate logical switch ARP and ND replies.  Since ipam
already looks at logical router ports, the only ipam modification
necessary is to skip logical switch ports with addresses "router".

Signed-off-by: Mickey Spiegel <mickeys.dev@gmail.com>
Acked-by: Ben Pfaff <blp@ovn.org>
Signed-off-by: Ben Pfaff <blp@ovn.org>