zebra: handle protodown netlink for vxlan device

zebra: handle protodown netlink for vxlan device

Frr need to handle protocol down event for vxlan
interface.
In MLAG scenario, one of the pair switch can put
vxlan port to protodown state, followed by
tunnel-ip change from anycast IP to individual IP.

In absence of protodown handling, evpn end up
advertising locally learn EVPN (MAC-IP) routes
with individual IP as nexthop.
This leads an issue of overwriting locally learn
entries as remote on MLAG pair.

Ticket:CM-24545
Reviewed By:CCR-10310
Testing Done:

In EVPN deployment, restart one of the MLAG
daemon, which puts vxlan interfaces in protodown state.
FRR treats protodown as oper down for vxlan interfaces.
VNI down cleans up/withdraws locally learn routes.
Followed by vxlan device UP event, re-advertise
locally learn routes.

Signed-off-by: Chirag Shah <chirag@nvidia.com>