Don't cast CONNECTING msgs to CONNECTED.

Fixed some logic in TelephonyRegistry so its notion of the state of our connection is
preserved, but it still sends out proper CONNECTING msg on secondary APNS (ie, bringing
up mms while the default connection was already up - it used to send out two CONNECTING
msgs instead of one CONNECTING and one CONNECTED).

Fixes mms while on mobile data.

bug:2840564
Change-Id: I69159aa0f471396680615ce6b9785620d844968f