zebra: Do not allow delete of route from kernel in non-startup case

zebra: Do not allow delete of route from kernel in non-startup case

This is a continuation of 915902cb82cfd.  Basically the netlink
read of messages up from the kernel is now noticing the proper
owner of the route.  As such when rib_delete was being called
as part of the upcall from the kernel we were not noticing that
we were the originator and not diss-allowing the rib_delete
from happening.  This restores this behavior that we were getting
pre-915902cb82cfd

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>