qcacmn: Add new cdp API to get vdev in monitor mode

After gerrit#2436786, vdev in monitor mode is removed from vdev
list of pdev. So it is needed to add one more cdp API to get vdev
in monitor mode.

CRs-Fixed: 2343290
Change-Id: I9d74302a464280881ce0cf25dbc8c4f9d8b8d48d
3 files changed