When Data RAT changes the new RAT retry connectable APN's

Issue: In the scenario where phone is in LTE and has data up and running, then user makes a voice
 call. During voice call, devices moves out of LTE coverage and moves into 1X. Since 1X does not
 support simultaneous voice and data, the data call will be dropped. When the device moves back
 into LTE coverage later, device does not attempt to set up the data call again until the voice
 call is ended. This causes the data stall.
Fix: register for EVENT_DATA_RAT_CHANGED and attempt SETUP_DATA_CALL upon receiving this event.

Change-Id: Ibe9e68295661f2f2ffaca3057d696df6a1db3f0c