bgpd: parse and comapre rmac attr against self mac

bgpd: parse and comapre rmac attr against self mac

Any evpn bgp update message comes with router mac extended
community, which can potentially contain the madd adddress
same as any of the local SVIs (L3VNI) MAC address.
Set route mac exist and during route processing in
bgp_update() filter the route.

Ticket:CM-23674
Reviewed By:CCR-8336
Testing Done:
Configure L3vni mac on TORS1 which is similar to TORC11
L3vni MAC. When TORC11 received the EVPN update with
Router mac extended community, this check rejected the
BGP update message.

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