Fix inconsistent columns when appending cursor data

1. To ensure the number of columns in both cursor is the same when
appending cursor data, so invoke to.getString() to add null in the case
of data is null.

2. Add a conidition that filter carrier id is not UNKNOWN_CARRIER_ID to
prevent the carrier id is unkown at SIM_LOCK and Telephonyprovider
return the APN with unknown carrier id.

Test: By manual
Bug: 147158852
Change-Id: I72995f53d350b9c9f28fa50f14362d62cfefc4ac
1 file changed