Add deviation not-supported for "link-up-down-trap-enable"

[jovatn]

It's possible to set "link-up-down-trap-enable" per interface, and the setting is accepted.

admin@infix-00-00-00:/config/> show interfaces
interface e1 {
  type etherlike;
  link-up-down-trap-enable enabled;
  ipv6
}
...

But it does not do anything, I hope. And we have no support to set a remote SNMP trap host either.
I suggest we add a deviation in infix-interfaces to remove the setting until we have support for it, if ever.