bgpd: l3vni del to free ip prefix routes from vrf

bgpd: l3vni del to free ip prefix routes from vrf

In Symmetric routing case, L3VNI stores evpn MAC_IP routes
as IP_PREFIX routes in associated bgp_vrf and fib.

When vxlan device for l3vni goes down, triggers l3vni delete
in bgp.
As part l3vni delete, evpn ip prefix routes associated
with the vni need to be withdrawn from zebra as well
bgpinfo needs to be freed.
bgp_delete does not free bgp_info associated
to evpn ip prefix routes (link to bgp_vrf).
Call to uninstall_evpn_route_entry_in_vrf() properly
cleanup bgp_info as well triggers appropriate updates.

Ticket:CM-21443
Testing Done:
On DUT, bringup symmetric routing configuration, learn
EVPN Type-2 and Type-3 Routes.
Type-2 MAC_IP routes will be stored as ip_prefix in vrf table
during l3vni bring up.

Remove L3vni, deletes all ip_prefix routes from the zebra, kernel
vrf route table and bgp_info is freed.

Check the show bgp memory stats for bgp_info post l3vni flap.

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