fix: dev: switchd crash fix
fix: dev: switchd crash fix

With recent changes to add Neighbor entries proactively, we add neighbor entries without port reference and mac, till the arp is resolved.
And if user does no routing before the port/mac is populated, there is some check in switchd which need null port validation.

TG-1769

Change-Id: I9c1c7363126670a9fbb8533697d880816d94ede4
Signed-off-by: Sourav Dutta <c4a3d3b2d4a9588486a42a058923adc8836ced21@hpe.com>

open-switch/ops-switchd,open-switch/ops-switchd,open-switch/ops-switchd