Fixed a crash when data network does not have PCO

Avoid crash when PCO data arrives, but it's only for certain data
networks but not all, it will crash in data network controller
when trying get PCO data from each network.

Test: Able to repro with unit test. Verified working after fix.
Fix: 242768045
Merged-In: I832ddcc80f4e92d487bd0fa93ec63f74e4978de3
Change-Id: I832ddcc80f4e92d487bd0fa93ec63f74e4978de3