Fix ConcurrentModificationException happens while calling API getPreferredApn

The API getPreferredApn is not a thread-safety method, once both the main thread
and the work thread of the data connection call it at the same time, violating
thread-safety issue will happen.

To fix it, pass a parameter named as isApnPreferred from DcTracker to the data
connection.

Change-Id: I42d1c05dc441e5d5429c9b35960db08f99062a14
CRs-Fixed: 2601981