ospfd: add dead-interval 40 if configured in show running

ospfd: add dead-interval 40 if configured in show running

Problem Statement:
==================
When hello-interval is configured as 5, automatically dead interval becomes
4 times of hello i.e 20 seconds. But user wants the dead interval as
40 seconds and hello as 5 seconds. Therefore user configures it.
Now "ip ospf dead-interval 40" is not shown in "show running-config"
Therefore when user restarts the daemon, the dead interval goes back to
20 seconds and the neighbors are down.

Fix:
==================
If user configures dead-interval as 40, show it in show running config.

Fixes: #9401
Signed-off-by: Mobashshera Rasool <mrasool@vmware.com>
(cherry picked from commit 2c1f2d2ad963259dd9534da87c178bdac873e765)