qcacld-3.0: offload tx packets freq update for virtual mon

Freq information not received from FW for offloaded tx frames.
Now FW will send freq information of offload tx frames using
existing htt interface reserved field. Update freq of offload
tx packets, received in reserved field.

Change-Id: I816844b2ea242fb813d6ab2ddb54aa3acab118d9
CRs-Fixed: 2557379