Only shows roaming disconnect notificaiton once

If data connection is not allowed due to data roaming
not enabled, we should only show the notification once
before data is connected again.

Fixed by reverting part of ag/2163254.

Test: Telephony sanity tests
bug: 38279959
Change-Id: I423063809e8814817b53ef97a0bd53df04cfc043
1 file changed