Better matching of PCO data to DataConnections

There appears to be latency between the Dc connecting and
the DcController learning about it.  Try other options:
 - look into each Dc to see if it has the cid set
 - look for a Dc with CONNECTING ApnContext

bug:29624199
Change-Id: I20e34ff38491a5d1ae404b37704d66642adbf064