qcacmn: Add serialization command to get disconnect stats

Currently for SAP case on the disconnection with the
client, host driver sends get stats command for the
disconnected peer to the FW and proceeds with the peer
deletion. There is a race condition where if the peer
gets deleted in the object manager before FW sends the
requested stats in that case host driver drops the
response from the FW.

To resolve above issue send the get stats request command
in serialization before peer delete command gets serialized
which will ensure that get stats response is processed
before peer delete in the object manager.

Change-Id: Iaa63e299ddfd3ca46c80bd79c3461c183fc0a62f
CRs-Fixed: 2664328