Update ATT Phone APN to bring in-line with ATT's current APNs

Change-Id: I762100a56c055e59c3f51560b29616dc6e085d2c
Signed-off-by: jakew02 <jacob.whatley91@gmail.com>
Merge "Update ATT Phone APN to bring in-line with ATT's current APNs" into cm-10.2