zebra: reinstate bgp route on local delete

zebra: reinstate bgp route on local delete

Neigh detected duplicate detected during local update,
upon receiving kernel neigh delete, set neigh inactive
flag so BGPd can install remote route entry if present.

Only if freeze action enabled, local duplicate detected
entry will not be present in BGPd thus marking neigh
inactive is safe. BGPd will simply attempt install
remote entry if present.

Ticket:CM-23438
Testing Done:
Validated MAC-IP pair, trigger mobility of between two
VTEPs, upon local freeze perform neigh delete which
triggers BGP to install remote type-2 route into kernel.

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