qcacmn: Release vdev ref in scan fail cases

Currently thr driver fails to release the ref count of vdev
at several places in the scan path which can lead to vdev
leak.

Fix is to release the ref count of the vdev in case of error
conditions.

Change-Id: I80ec7fb648d23e5fd3e91b2ca5638a2b4c280251
CRs-Fixed: 2392491