Telephony: Allow setDefaultDataSubId to be called multiple times

- Allow setDefaultDataSubId() to be called on same subscription
multiple times without causing PS DETACH on that sub.
- Call setDefaultDataSubid() after bootup.
- Inform OemHookDdsService about default DDS even during on-demand
PS attach requests.

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

Change-Id: I7e40998e1ff239e2cd6360568d217b801a475da9