zebra: Uninstall remote MACs from kernel appropriately

zebra: Uninstall remote MACs from kernel appropriately

When a remote MAC goes away, but there are neighbors referring to it,
ensure that when the last remote neighbor goes away, the MAC is
uninstalled from the kernel and no longer considered as remote.

Signed-off-by: Vivek Venkatraman <vivek@cumulusnetworks.com>
Reviewed-by:   Anuradha Karuppiah <anuradhak@cumulusnetworks.com>
Reviewed-by:   Chirag Shah <chirag@cumulusnetworks.com>
Ticket: CM-22130
Reviewed By: CCR-7777
Testing Done:
1. Replicated failed scenario and verified with fix.
2. evpn-min