VOL-1030 Ignore flow update if OLT is operational down.
VOL-1030 Ignore flow update if OLT is operational down.

This solves the hang issue when openolt driver is killed
and possibly helps with a sneaky voltha hang issue seen
when the system is left to run for long time. It helps
while the root cause is investigated.

Change-Id: Ib73d6f1dd869f56d266b385c085e976ccca4cc17

opencord/voltha,opencord/voltha,opencord/voltha,opencord/voltha,opencord/voltha