Fix data call can't be applied after Phone restart in APM on under IWLAN

1. This fix is used to address some corner cases, e.g. Telephony
has no a chance to query network state change after phone restarted
under APM ON. In case of radio power off, after phone restarted,
Telephony only polls state according to modem's event because the
previous IWLAN RAT state is reset. If RIL doesn't report again,
Telephony has no chance to query network state.

2. Telephony needs to persist the current APN transport because qualified
network service can't send the available without a preferred RAT at that
time.

To fix it, inform network state changed event after service is
connected and persist the current APN transport.

Change-Id: I6f6251519ea76c4c0f6c164fb6e268ebeef23415
CRs-Fixed: 2556765