Fix contacts crash due to presence information.

It looks like the presence code must be nulling out the carrier presence
column, which is something the original presence code in Contacts did not
account for.

Adding appropriate null condition check and fallback.
Note: This will need to be cherry-picked into a more recent
ubcontacts branch to ensure the prebuilt contacts app is updated.
For now the AOSP Contacts app builds and works fine.

Bug: 28292990
Change-Id: I08cc54cc1e821c502b0801f692bd03d277b9cc46