Gateway client registration don't honor expires from server in specific case

[gmaruzz]

In this case:

https://github.com/signalwire/freeswitch/issues/1511

Freeswitch keeps its own expire, even if server change it

So, if server gives back an expires that is lower than freeswitch one, registration will not be present on server

[gmaruzz]

actually, this happens only if the Contact: sent by server contains a different ip address from the Contact that was sent by freeswitch

if this happens, instead of giving a warning or error, and instead of honoring the expires: in Contact, freeswitch keeps its own expires and works as Contact was correct and no expires was set in it by the server

expected behavior: OR give a warning/error OR honor the expires set by server