bgpd: evpn pip parse vrr mac

bgpd: evpn pip parse vrr mac

In L3VNI add callback parse, vrr rmac value.

For non-zero vrr mac value, use it as anycast RMAC
and svi mac as individual rmac value.

If advertise-pip is disable or vrr rmac is not present
use svi mac as anycast rmac value for all routes.

Ticket:CM-26190
Reviewed By:
Testing Done:

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