Telephony: Implement Data+MMS functionality

- DSDA: Allow simultaneous on-demand PDN activation on either sub.
- 7+5 mode functionality: Differentiate between permanent
  and temp DDS switches.
- ALLOW_DATA failure retries implementation.

Conflicts:
	src/java/com/android/internal/telephony/dataconnection/DcSwitchAsyncChannel.java
	src/java/com/android/internal/telephony/dataconnection/DctController.java

Change-Id: Iff9e847a76bd46215569b566db412667ba8ed008